Combo Box Won't Fill

[dccjr]

I have several combo boxes whose Row Source changes based on a selection in a previous combo box. Some are simple Add Item, while most are filled from SQL statements. I had one working, but the next time I tried (no changes), it would not fill the next combo box. Below is the code for the user form. I don't know if I am doing something wrong nesting Select Case statements, or what. I have tried googling a solution, but there are not any examples of what I am trying to do. My lack of knowledge and experience has me seaching blindly. Any suggestions would be great.

Option Compare Database
Option Explicit
'Private Sub ReportsChartsClear()
'    Me.cboRptType.Value = "Select Report or Chart Type"
'    Me.cboConstraint.RowSource = ""
'    Me.cboConstraint.Value = "Select Contraint"
'    Me.cboConValue.RowSource = ""
'End Sub
'Private Sub frmReportsCharts_Load()
'    ReportsChartsClear
'End Sub
'Private Sub frmReportsCharts_GotFocus()
'    ReportsChartsClear
'End Sub
Private Sub cmdHome_Click()
    DoCmd.Close acForm, Me.Name
    DoCmd.OpenForm "frmHome"
End Sub
Private Sub cboRptType_Change()
    Select Case Me.cboRptType.Value
        Case "Pareto Chart"
           cboConstraint.AddItem "Event Type"
           cboConstraint.AddItem "Event Category"
           cboConstraint.AddItem "Work Area/Cell"
           cboConValue.Enabled = False
           txtStartDate.Enabled = False
        Case "RCA Event Report"
            cboConstraint.AddItem "Work Order #"
            cboConstraint.AddItem "Quality #"
            cboConValue.Enabled = True
            txtStartDate.Enabled = False
        Case "RCA Event Summary List"
            cboConstraint.AddItem "Specific Date to Present"
            cboConstraint.AddItem "Work Area/Cell"
            cboConstraint.AddItem "Event Type"
            cboConstraint.AddItem "Event Category"
    End Select
End Sub
Private Sub cboConstraint_AfterUpdate()
    Dim strEventSQL As String
    Dim strSummarySQL As String
    Dim strParetoSQL As String
    Dim RstCount As Integer
    Dim dtmStart As Date
    Dim qdf As DAO.QueryDef
    
    Me.txtStartDate.Text = dtmStart
    'strEventSQL , strSummarySQL, strParetoSQL, strConValue.RowSource = ""
     
    Select Case Me.cboRptType.Value
        Case "RCA Event Summary List"
            MsgBox "This option generates a Summary Report based on non-exclusive criteria. All records meeting this non-exclusive criteria will be displayed."
            Select Case Me.cboConstraint.Value
                Case "Specific Date to Present"
                    Me.txtStartDate.Visible = True
                    Me.cboConValue.BackColor = RGB(255, 255, 0)
                    Me.cboConValue.Text = "Multiple Records Report"
                    Me.cboConValue.Locked = True
                    strSummarySQL = "SELECT (*) FROM RCAData1 WHERE RCAData1.StartDate > '" & Me.txtStartDate.Value & "' ORDER BY RCAData1.DefectDate DESC;"
                Case "Part Number"
                    strSummarySQL = "SELECT RCAData1.PartNo FROM RCAData1 ORDER BY RCAData1.DefectDate DESC;"
                    Me.cboConValue.RowSource = strSummarySQL
                    Me.cboConValue.Requery
                Case "Work Area/Cell"
                    strSummarySQL = "SELECT DISTINCT RCAData1.AreaCell FROM RCAData1 ORDER BY RCAData1.AreaCell DESC;"
                    Me.cboConValue.RowSource = strSummarySQL
                    Me.cboConValue.Requery
                Case "Event Type"
                    strSummarySQL = "SELECT DISTINCT RCAData1.Type FROM RCAData1 ORDER BY RCAData1.Type DESC;"
                    Me.cboConValue.RowSource = strSummarySQL
                    Me.cboConValue.Requery
                Case "Event Category"
                    strSummarySQL = "SELECT DISTINCT RCAData1.Category FROM RCAData1 ORDER BY RCAData1.Category DESC;"
                    Me.cboConValue.RowSource = strSummarySQL
                    Me.cboConValue.Requery
            End Select
        Case "RCA Event Report"
            Select Case Me.cboConstraint.Value
                Case "Work Number #"
                    strEventSQL = "SELECT RCAData1.WorkOrderNo FROM RCAData1 ORDER BY RCAData1.DefectDate DESC;"
                    Me.cboConValue.RowSource = strEventSQL
                    Me.cboConValue.Requery
                Case "Quality #"
                    strEventSQL = "SELECT RCAData1.QualityNo FROM RCAData1 ORDER BY RCAData1.DefectDate DESC;"
                    Me.cboConValue.RowSource = strConstraintSQL
                    Me.cboConValue.Requery
            End Select
        Case "Pareto Chart"
            Select Case Me.cboConstraint.Value
                Case "Work Area/Cell"
                    strParetoSQL = "SELECT RCAdata1.AreaCell, COUNT(*) as 'Number of Events' FROM RCAData1 GROUP BY RCAData1.AreaCell;"
                Case "Event Type"
                    strParetoSQL = "SELECT RCAdata1.EventType, COUNT(*) as 'Number of Events' FROM RCAData1 GROUP BY RCADAta1.EventType;"
                Case "Event Category"
                    strParetoSQL = "SELECT RCAdata1.Category, COUNT(*) as 'Number of Events' FROM RCAData1 GROUP BY RCAData1.Category;"
            End Select
    End Select
    
End Sub
Private Sub cmdGenRpt_Click(ByVal strEventSQL As String, ByVal strSummarySQL As String, ByVal strParetoSQL As String)
    Dim intQty As Integer
    Dim RstCount As Integer
    Dim dtmStart As Date
    Select Case Me.cboRptType.Value
        Case "Pareto Chart"
            DoCmd.Close acForm, Me.Name, acSaveNo
            DoCmd.OpenReport "ParetoChart", , , strParetoSQL
        Case "RCA Event Report"
            DoCmd.Close acForm, Me.Name, acSaveNo
            DoCmd.OpenReport "RCAEventReport", , , strEventSQL
        Case "RCA Event Summary List"
            DoCmd.Close acForm, Me.Name, acSaveNo
            DoCmd.OpenReport "RCASummaryReport", , , strSummarySQL
     End Select
End Sub

[Rod]

Difficult to help from the information supplied. 'Option Explicit' - good! Does it compile - I assume so. Have you tried putting in a checkpoint and stepping through the code? Using the On_Change event for a combo box is an unusual choice but won't produce the effect you're experiencing. Nested Select Case statements should be no problem. Are you sure your SQL returns a result set? No date comparisons that I can see so that difficulty does not happen.

Where do you empty the rows of cboConstraint? I see where you add items but not where you clear/empty them.

Really this is a case for detailed debugging.