[AccessD] Need help with controls on a subform

Hi Folks

I have an event database, and I am having trouble with referencing controls
on a subform.

Using a command button (cmdShowTier1) on the main form (frmEvents), I want
to change the border color on selected textboxes on the subform
(sfrmEventSectionLeft). Each field (EventSeatA001 through EventSeatR023) in
the subform has a TAG property set to "Tier1", "Tier2" or "Tier3". Below is
the code. The commented-out MsgBox lines were for trouble-shooting only.

CODE SAMPLE
============================================================================
=================
Function ShowTier3()

Dim ctl As Control

Forms![frmEvents]![sfrmEventSectionLeft].SetFocus
Forms![frmEvents]![sfrmEventSectionLeft].Form![EventSeatA001].SetFocus

For Each ctl In Me.Controls
'MsgBox "The focus is on " & ctl.Name
    If ctl.ControlType = acTextBox Then
        If ctl.Tag = "Tier3" Then
            ctl.BorderColor = vbBlue
        End If
    End If
Next ctl

Forms![frmEvents].SetFocus

End Function
Function HideTier3()

Dim ctl As Control

Forms![frmEvents]![sfrmEventSectionLeft].SetFocus
Forms![frmEvents]![sfrmEventSectionLeft].Form![EventSeatA001].SetFocus

For Each ctl In Me.Controls
'MsgBox "The focus is on " & ctl.Name
    If ctl.ControlType = acTextBox Then
        If ctl.Tag = "Tier3" Then
            ctl.BorderColor = vbBlack
        End If
    End If
Next ctl

Forms![frmEvents].SetFocus

End Function
Private Sub cmdShowTier3_Click()
On Error GoTo Err_cmdShowTier3_Click

cmdHideTier3.Visible = True
cmdHideTier3.SetFocus
cmdShowTier3.Visible = False

ShowTier3
'MsgBox "Tier 3 seats should now be blue", vbOKOnly

Exit_cmdShowTier3_Click:
    Exit Sub

Err_cmdShowTier3_Click:
    MsgBox Err.Description
    Resume Exit_cmdShowTier3_Click
    
End Sub
Private Sub cmdHideTier3_Click()
On Error GoTo Err_cmdHideTier3_Click

cmdShowTier3.Visible = True
cmdShowTier3.SetFocus
cmdHideTier3.Visible = False

HideTier3
'MsgBox "Tier 3 seats should now be black", vbOKOnly

Exit_cmdHideTier3_Click:
    Exit Sub

Err_cmdHideTier3_Click:
    MsgBox Err.Description
    Resume Exit_cmdHideTier3_Click
    
End Sub
============================================================================
=================

The code moves the focus to the subform, but the Me.Controls just cycles
through the main form.

How do I reference the subform, so that the proper fields are updated?

I really appreciate any help or suggestions.

Thanks,
Bob Gajewski