AjaxControlToolkit AutoCompleteExtender is not displaying suggestions

I am using AutoCompleteExtender in asp.net to fetch name and designation based on token(empno). The is pulled from database and I could see it in the network tab of Chrome Dev-tools. But it is not rendered as suggestion list.

My attempt for the code:

<div class="modal-body">                        
                     <div class="form-group">
                        <label for="pToken">Token</label>
                         <asp:TextBox ID="pToken" runat="server" CssClass="form-control" placeholder="Enter Token No" />                           
                         <ajaxcontrol:AutoCompleteExtender runat="server" 
                                    ID="acToken" TargetControlID="pToken" MinimumPrefixLength="3"
                                    EnableCaching="true" FirstRowSelected="false" 
                                    ServiceMethod="getPatients" ServicePath="CheckPatientDetails.aspx"
                                    CompletionSetCount="6" DelimiterCharacters="|"
                                    CompletionListItemCssClass="AutoCompleteExtender_CompletionListItem"
                                    CompletionListHighlightedItemCssClass="AutoCompleteExtender_HighlightedItem"
                                    CompletionListCssClass="AutoCompleteExtender_CompletionList">
                          </ajaxcontrol:AutoCompleteExtender>
                     </div>
                    <div class="form-group">
                        <label for="pName">Name</label>                            
                        <asp:TextBox ID="pName" runat="server" CssClass="form-control" placeholder="Enter patient name" required />
                    </div>
                    <div class="form-group">
                        <label for="pDesig">Designation</label>                            
                        <asp:TextBox ID="pDesig"  runat="server" CssClass="form-control" placeholder="Enter designation" />
                    </div>
                    <div class="form-group">
                        <label for="pType">Type</label>                            
                        <asp:DropDownList ID="pType" runat="server" CssClass="form-control" required>
                            <asp:ListItem Value="E" Selected="True">Employee</asp:ListItem>
                            <asp:ListItem Value="I">In Patient</asp:ListItem>
                            <asp:ListItem Value="O">Out Patient</asp:ListItem>                        
                            <asp:ListItem Value="X">Others</asp:ListItem>                                
                        </asp:DropDownList>                            
                    </div>

The backend code for the same is below :

[WebMethod]
    [System.Web.Script.Services.ScriptMethod()]
    public static List<Patient> getPatients(string prefixText, int count)
    {
        List<Patient> patientList = new List<Patient>();
        OracleConnection con = null;
        OracleDataReader odr = null;

        string query = "select nvl(emp.empid,'') token,DECODE(SHORTNAME,NULL,FIRSTNAME,SHORTNAME)  name,DESIGSHORT desigdesc" +
                        " from employee emp join designation desig  on (emp.desigcode = desig.desigcode and desig.isactive = 'Y') " +
                        " where empid like '%" + prefixText + "%' and emp.EMPSTATUS = 'A' order by empid";
        try
        {
            con = getHRMSConnection();
            con.Open();
            using (con)
            {
                using (OracleCommand cmd = new OracleCommand(query, con))
                {
                    odr = cmd.ExecuteReader();
                    Patient patient = null;
                    while (odr.Read())
                    {
                        patient = new Patient();
                        patient.setToken(Convert.ToString(odr["token"]));
                        patient.setName(Convert.ToString(odr["name"]));
                        patient.setDesignation(Convert.ToString(odr["desigdesc"]));
                        patientList.Add(patient);
                    }

                }
            }
        }
        catch (Exception ex)
        {

        }
        return patientList;
    }

The task is done now, I am getting the autocomplete rendered properly. Posting for those who may refer to this later on.

I used this link to get the autocomplete rendered on modal. Autocomplete extender not working inside modal popup extender

Now my modal body is

 <div class="modal-body">             
                     <div class="form-group">             

                    <asp:AutoCompleteExtender ServiceMethod="GetSearch" MinimumPrefixLength="2" CompletionInterval="10"  
                        EnableCaching="false" CompletionSetCount="10" TargetControlID="pToken" ID="AutoCompleteExtender2"  
                        runat="server" FirstRowSelected="false" CompletionListCssClass="autocomplete_completionListElement" CompletionListItemCssClass="autocomplete_listItem" 
                        CompletionListHighlightedItemCssClass="autocomplete_highlightedListItem">  
                    </asp:AutoCompleteExtender>  
                    <label for="pToken">Token</label>                        
                    <asp:TextBox ID="pToken" runat="server"  CssClass="form-control" placeholder="Enter Token No"/>                

                     </div>
                    <div class="form-group">
                        <label for="pName">Name</label>                            
                        <asp:TextBox ID="pName" runat="server" CssClass="form-control" placeholder="Enter patient name" required />
                    </div>
                    <div class="form-group">
                        <label for="pDesig">Designation</label>                            
                        <asp:TextBox ID="pDesig"  runat="server" CssClass="form-control" placeholder="Enter designation" />
                    </div>
                    <div class="form-group">
                        <label for="pType">Type</label>                            
                        <asp:DropDownList ID="pType" runat="server" CssClass="form-control" required>
                            <asp:ListItem Value="E" Selected="True">Employee</asp:ListItem>
                            <asp:ListItem Value="I">In Patient</asp:ListItem>
                            <asp:ListItem Value="O">Out Patient</asp:ListItem>                        
                            <asp:ListItem Value="X">Others</asp:ListItem>                                
                        </asp:DropDownList>                            
                    </div>
                </div>

And server side code is :

[WebMethod]
    [System.Web.Script.Services.ScriptMethod()]
    public static List<string> GetSearch(string prefixText, int count)
    {

            OracleConnection con = null;
            OracleDataAdapter oda = null;
            DataTable dt;
            prefixText = prefixText.ToLower();
            DataTable Result = new DataTable();
            List<string> Output = new List<string>();

            string str = "select nvl(emp.empid,'') ||'('||DECODE(SHORTNAME,NULL,FIRSTNAME,SHORTNAME)||','|| DESIGSHORT ||')' employee" +
                           " from employee emp join designation desig  on (emp.desigcode = desig.desigcode and desig.isactive = 'Y') " +
                           " where lower(empid) like '%" + prefixText + "%' and emp.EMPSTATUS = 'A' order by empid";
            con = getHRMSConnection();
            using (con)
            {
            try
            {
                con.Open();
                oda = new OracleDataAdapter(str, con);

                dt = new DataTable();
                oda.Fill(dt);

                for (int i = 0; i < dt.Rows.Count; i++)
                {
                    Output.Add(dt.Rows[i][0].ToString());
                }

            }
            catch (Exception ex)
            {

            }
        }

        return Output;
    }