Paging is Not working Properly in Gridview

When I search the Data by using Two Textboxes and Press Button the Data is Filled in Gridview. I set Allow Paging =True.When i Try to move from First Page to Second Page in Gridview ,gridview will dissapper. My Code

<asp:GridView runat="server" ID="Gv1" EmptyDataText="No Recorde Found"             
         AllowPaging="true" AutoGenerateColumns="false" PageSize="10"       
         OnPageIndexChanging="Gv1_PageIndexChanging" 
         OnRowCommand="Gv1_RowCommand" >

--

protected void Gv1_PageIndexChanging(object sender, GridViewPageEventArgs e)
{
   Gv1.PageIndex = e.NewPageIndex;
   LoadGrid();
}

Try like this

  protected void btnSearch_Click(object sender, EventArgs e) 
  {
     if (ddl1.SelectedIndex > 0 )
     {
          x = ddl1.SelectedItem.ToString();
      } 

      if (ddl2.SelectedIndex > 0) {
          y = ddlProgram.ddl2.ToString(); 
      } 

      BindGrid();
 }

private void BindGrid() {
 if (ViewState["mySearchedData"] != null) {
    gv.DataSource = ViewState["mySearchedData"];
    gv.DataBind();
 }
 else 
 {
    gv.DataSource = wcfobj.GetData(x,y);
    gv.DataBind();
    ViewState["mySearchedData"]= wcfobj.GetData(x,y);
  }
 }