error during selection in filter of non matching values. error: Index was out of range

use page_error to catch...and page_load to set the session

page load:

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        If Session("Filter Error") = "true" Then
            ScriptManager.RegisterStartupScript(Me, Me.[GetType](), "Filter", "alert('No such criteria was matched with the database.')", True)
        End If
        Session("Filter Error") = "false"

page error:

Protected Sub Page_Error(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Error
        ' BEGIN - catching errors due to referential integrity constraints
        ' getting the exception
        Dim objErr As Exception = Server.GetLastError().GetBaseException()
        Dim tempMsg As String
        Dim tempStrAndErrCompDELETE As Boolean
        Dim tempStrAndErrComp As Boolean
        Dim tempStrAndErrCompINDEX As Boolean REM testing!!!
        ' getting the message from objerr (the real exception raised)
        Dim tempErrorMessage As String
        tempErrorMessage = objErr.Message.ToString()
        ' comparing variables for violations
        tempStrAndErrCompDELETE = tempErrorMessage.Contains("DELETE")
        tempStrAndErrComp = tempErrorMessage.Contains("")
        tempStrAndErrCompINDEX = tempErrorMessage.Contains("Index was out of range") REM testing!!!
        ' looking for DELETE violation
        If (tempStrAndErrCompDELETE = True) Then
            tempMsg = "This is a non-critical error. There was an error during DELETE operation. This was because the record you tried to delete is already being used. If a record is already being used in another table then deleting it would also delete its entry from there and that would create null references. For further explanation of this please contact Saad Hashmi, Asst. IT Programmer." _
                      + Environment.NewLine + " Error: " + tempErrorMessage
            Server.Transfer("TempErrorAdmin.aspx?request_tempMsg=" + tempMsg)
            ' looking for INDEX violation (because of selecting wrong values in FILTER)
        ElseIf (tempStrAndErrCompINDEX = True) Then
            'Response.Redirect("default.aspx")
            ' ScriptManager.RegisterStartupScript(Me, Me.[GetType](), "Filter", "alert('No such criteria was matched with the database.')", True)
            'ScriptManager.RegisterStartupScript(Me, Me.[GetType](), "Updated", "alert('Successfully Updated')", True)
            Session("Filter Error") = "true"
            REM Since the popup alert did not get displayed therefore adding a timer to response redirect for 0 seconds.
            REM The reason for response redirect in first place is because multiple records were being added on refresh.
            Response.AddHeader("REFRESH", "0;Data_Entry_Form.aspx")
            ' looking for GENERAL violation
        ElseIf (tempStrAndErrComp = True) Then
            tempMsg = "This is a critical general error. For further explanation of this please contact Saad Hashmi, Asst. IT Programmer." _
                    + " Error: " + tempErrorMessage
            Server.Transfer("TempErrorAdmin.aspx?request_tempMsg=" + tempMsg)
        End If
        ' clearing the server error raised
        Server.ClearError()
    End Sub