On Postback placeholder controls disappearing

Within my webpage I am loading usercontrols within a placeholder. Each of these user controls triggers a postback when an ajaxcontroltoolkit rating is changed. The problem I am having is that if I use

If (Not IsPostBack is Nothing)

the controls within the placeholder disappear on post.

My Page_Load looks like this currently

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    Session("ProId") = Nothing
    Session("FolId") = Nothing
    Dim ProId As Integer
    If (Not Request.QueryString("ProjectID") Is Nothing) Then
        ProId = Convert.ToInt32(Request.QueryString("ProjectID").ToString())
        Session("ProId") = Request.QueryString("ProjectID").ToString()
    End If
    Dim FolId As Integer
    If (Not Request.QueryString("FolderID") Is Nothing) Then
        FolId = Convert.ToInt32(Request.QueryString("FolderID").ToString())
        Session("FolId") = Request.QueryString("FolderID").ToString()
    End If
    objUser = New BSSiteUser(CInt(Page.User.SiteUser.intID))
    objProject = New BSProject(ProId)
    objFolder = New BSFolder(objUser.SiteUserID, FolId)
    objOrganization = New BSOrganization(objProject.intOrganizationID, objUser.SiteUserID)
    Me.Load_SubcontractorList()
    Me.Load_EvaluationList(1)
    Me.Load_EvaluationList(2)
    Me.lblorganization.Text = objOrganization.CompanyName
    Me.lblprojectname.Text = objProject.strProjectName
    Me.lblprojectnumber.Text = objProject.strProjectNumber
    Me.lbldatecreated.Text = Date.Now.Date.ToString()
End Sub

The Load_EvaluationList is what loads the user controls, if I place the IsPostBack check around those two, the controls disappear, what could be the problem

I am abandoning this question as a decision was made to go a different route