Combobox Not Populating With RowSource Set in The Control's Properties

[Ark68]

Would anyone be able to help isolate the possible cause of a particular problem I am having populating a combobox control on my userform?

1. From userform test_mr, the user clicks on an entry in listbox miss_nr

Private Sub miss_rn_Click()

    Debug.Print Me.Name, ".miss_rn_Click() called"
    
    With miss_rn
        Debug.Print Me.Name, ".miss_rn_Click() ListIndex: " & .ListIndex & " (" & .List(.ListIndex) & ")"
        group_1.Show
    End With
    mbEvents = True
End Sub

2. This in turn opens up userform group_1

Public Sub UserForm_Initialize()

    Dim l_mr As Long

    mbEvents = False
    Debug.Print df1
    
    l_mr = ws_vh.Range("B2") 'missing rental count in current schedule        'l_mr = 1
    Debug.Print l_mr
    Debug.Print agf
    
    'parking location of userform on desktop
    'group_1.Top = 300
    'group_1.Left = 500
    
    ws_vh.Range("A7:D7") = "" 'advanced filter criteria
    
    With TextBox1
        .Locked = False
        .BackColor = RGB(255, 255, 255)
        .Value = Format(0, "000000") 'new rental
        .SetFocus
        .SelStart = 0
        .SelLength = Len(.Text)
    End With
    If l_mr <> 1 Then uf2_eliminate.Visible = False
    If df1 < 4 Then uf2_eliminate.Visible = True
    Label34.Caption = "   Please enter valid permit number."
    proceed1.Enabled = True
    'uf2_eliminate.Visible = False
    submit1.Enabled = False
    delete1.Enabled = False
    edit1.Enabled = False
    amm_no.Value = 0
    amm_no.Locked = True
    date1.Value = Format(Date, "dd-mmm")
    date1.Locked = True
    ai_type.Value = ""
    ai_type.BackColor = RGB(0, 126, 167) 'celadon blue
    ai_function.BackColor = RGB(255, 255, 255)
    ai_function.Value = ""
    ai_function.Enabled = False
    ai_league.Value = ""
    ai_league.Enabled = False
    ai_calibre.Value = ""
    ai_calibre.Enabled = False
    ai_division.Value = ""
    ai_division.Enabled = False
    ai_event.Value = ""
    ai_event.Enabled = False
    
    MultiPage1.Value = 1
    MultiPage1.Visible = False
    MultiPage2.Value = 0
    Frame8.Visible = False
        
    group_1.Height = 124.5
    With TextBox1
        .BackColor = RGB(255, 255, 255)
        If l_mr > 0 Then 'this has come in from module 21 reporting missing rentals prior to workorder prep
            .Value = Format(test_mr.miss_rn.Value, "######")
            .BackColor = RGB(0, 168, 232)
            'ws_lists.Activate      'this made no difference
        Else
            .Value = Format(0, "######") 'new rental
        End If
        .SetFocus
        .SelStart = 0
        .SelLength = Len(.Text)
    End With
    mbEvents = True
End Sub

3. Since group_1 was referred to and opened from userform test_mr, a portion of group_1's fields are auto populated (textbox1). The user is then encouraged to press the "Process" commandbutton to proceed with additional data entry with group_1. (proceed1.click)

Private Sub proceed1_Click()
    
    Dim ty As Boolean
    Dim rng_pn As Range
    Dim rnl As Long
    Dim pn As Long
    Dim pn_exist As Boolean
    Dim lrow As Long
    
    
    Set rng_pn = ws_rd.Range("A:A")
    
    'check if numeric
    ty = IsNumeric(TextBox1.Value)
    If ty = False Then 'not a number
        Me.Label34.Caption = "    Permit numbers are 5 or 6 digit numeric values."
        Me.Label34.BorderColor = vbRed
        With TextBox1
            .Value = Format(0, "000000")
            .SelStart = 0
            .SelLength = Len(.Text)
            .SetFocus
        End With
        Exit Sub
    End If
    
    'check length
    rnl = Len(TextBox1.Value)
    If rnl < 5 Or rnl > 6 Then
        Me.Label34.Caption = "    Permit numbers are 5 or 6 digit numeric values."
        Me.Label34.BorderColor = vbRed
        With TextBox1
            .Value = Format(0, "000000")
            .SetFocus
            .SelStart = 0
            .SelLength = Len(.Text)
        End With
        Exit Sub
    End If
    
    'check value is valid
    If TextBox1.Value < 68000 Then
        Me.Label34.Caption = "    Invalid permit range."
        Me.Label34.BorderColor = vbRed
        With TextBox1
            .Value = Format(0, "000000")
            .SelStart = 0
            .SelLength = Len(.Text)
            .SetFocus
        End With
        Exit Sub
    End If
    
    'Valid permit number
    pn = TextBox1.Value
    Me.Label34.Caption = "    Valid permit number."
    Me.Label34.BorderColor = RGB(50, 205, 50)
        
    Me.TextBox1.Locked = True
    Me.proceed1.Enabled = False
    Me.date1.Locked = False
    Me.ai_type.SetFocus
    
    'check if rental exists in database
    pn_exist = WorksheetFunction.CountIf(rng_pn, pn) > 0
    
    'rental not in database

    If pn_exist = False Then
        TextBox1.BackColor = RGB(0, 126, 167)
        Me.Label34.Caption = "    Entry does not exist in database."
        Me.Label34.BorderColor = vbRed
        new_group pn
        
    'rental is in database
    Else
        lrow = Application.Match(pn, rng_pn, 0)
        mbEvents = False
        With Me
            .Caption = "USER GROUP     [E" & lrow & "]"
            .TextBox1.BackColor = RGB(50, 205, 50)
            .TextBox1.Locked = True
            .Label34.Caption = "    Rental already exists in the database."
            .Label34.BorderColor = RGB(50, 205, 50)
            'If Not mbEvents Then Exit Sub
            'mbEvents = False
            .Frame8.Visible = True
            .amm_no.Value = ws_rd.Range("B" & lrow).Value
            .amm_no.Locked = False
            '.amm_no.Locked = True
            .date1.Value = Format(ws_rd.Range("AO" & lrow), "DD-MMM")
            .date1.Locked = True
            .ai_type.Value = ws_rd.Range("C" & lrow)
            .ai_type.Locked = True
         
            .Height = 745
            .Top = 25
        
            .edit1.Enabled = True
            .delete1.Enabled = True
            
        End With
    End If
    'mbEvents = True

End Sub

4. Since pn_exist is false, procedure new_group (Blue code) is executed.

Sub new_group(ByRef pn As Long)
    Dim lrow_rd As Long
    Dim nrow_rd As Long

    lrow_rd = ws_rd.Cells(Rows.count, 1).End(xlUp).Row
    nrow_rd = lrow_rd + 1
    ws_vh.Range("E3") = 1
    With group_1
        .Top = 50
        .Caption = "USER GROUP     [N" & nrow_rd & "]"
        .Height = 252
        .ai_type.Locked = False
        Debug.Print ws_lists.Name
    End With
End Sub

5. With group_1 showing, textbox1 populated, the user is to select a value from combobox ai_type. The rowsource is coded into the control properties LISTS!A2:A10 . LISTS is a worksheet in the master workbook Sports17.xlsm. It is declared as a public worksheet ws_lists, and set = workbooks("Sports17.xlsm").worksheets("LISTS"). The debug line relates to the proper worksheet.

The combobox will not populate with the values in LISTS!A2:A10. It's just blank. If I use userform group_1 independent of steps 1 through 4 to enter new information (pn_exists=false), I have no problem with ai_type populating.

At this point in my project, the master workbook (Sports17.xlsm) is open, a source workbook (schedule.csv) is open and hidden, and a target workbook (Aug 11 2017 Data.xlsx) is also open.

Thank you all in advance for taking time to sort through this mess in an effort to help me.