Inconsistent Type Mismatch Error

[JTBorton]

Windows XP / Excel 2010 Pro.
I have a snippet of code that I use to format form controls based on user input. This code seems to run perfectly fine in one workbook, and not at all in another. The code in both workbooks is the exact same and both are located in a public module. The only possible difference I can see is that in the workbook that has no issues the control being passed is located in a userform; in the non-functioning workbook the same control is located on a spreadsheet.

If the FormatControl function is passed controls that are in a user form the function works just fine in both workbooks; whether I pass it a TextBox, ComboBox, ListBox, or any other MSForms library control. However, when I pass a MSForms library control that has been placed on a spreadsheet to the FormatControl function it crashes with a TypeMismatch error.

CheckCBOText is a special function for checking to make sure that users selected a value from a combo box control’s drop-down list instead of typing in a new value. The control is then forwarded to the FormatControl function for formatting. This function receives a combo box control with no problems, whether the control is located on a user form or a worksheet. However, if the combo box is located on a worksheet, I get a mismatch error when the control is forwarded to the FormatControl function for formatting.

Since the MSForms.Combox class inherits the MSForms.Control class, I cannot see why this error occurs, regardless of the location of the control. Can anyone provide any insight on the matter?

Public Enum enmControlFormat
    enmNoFormat = 1
    enmHasFocus = 2
    enmBadInfo = 3
    enmInfoRequested = 4
    enmInfoRequired = 5
End Enum

Public Function CheckCBOText(cboBox As MSForms.ComboBox, Optional NullStringAllowed As Boolean = True) As Boolean
    'Checks the text in a combo box to make sure it is valid.  Changes backcolor of the control accordingly.
    If cboBox.ListIndex < 0 And Trim(cboBox.Text) <> vbNullString Then
        [highlight]Call FormatControl(cboBox, enmBadInfo) [b][COLOR=red] Error Line[/color][/b][/highlight]
        CheckCBOText = False 
    Else
        Call FormatControl(cboBox, enmNoFormat)
        CheckCBOText = True
    End If
    If NullStringAllowed = False And Trim(cboBox.Text) = vbNullString Then
        Call FormatControl(cboBox, enmInfoRequired)
        CheckCBOText = False
    End If
    
End Function

Public Sub FormatControl(ctrControl As MSForms.Control, Optional FormatOption As enmControlFormat = enmNoFormat, Optional DefaultBackColor As Long = lngcFontColorWhite, Optional DefaultFocusColor As Long = lngcFontColorLightBlue)
    On Error Resume Next
    Select Case FormatOption
        Case enmBadInfo
            ctrControl.ForeColor = lngcFontColorDarkRed
            ctrControl.BackColor = lngcFontColorLightRed
            ctrControl.BorderStyle = fmBorderStyleSingle
            ctrControl.BorderColor = lngcBorderColorBad
            
        Case enmHasFocus
            ctrControl.ForeColor = lngcFontColorBlack
            ctrControl.BackColor = DefaultFocusColor
            ctrControl.BorderColor = lngcBorderColorBad 'Will not appear with no border
            ctrControl.BorderStyle = fmBorderStyleNone
            ctrControl.SpecialEffect = fmSpecialEffectSunken
            
        Case enmInfoRequested
            ctrControl.ForeColor = lngcFontColorBlack
            ctrControl.BackColor = lngcInfoRequiredColor
            ctrControl.BorderColor = lngcBorderColorBad 'Will not appear with no border
            ctrControl.BorderStyle = fmBorderStyleNone
            ctrControl.SpecialEffect = fmSpecialEffectSunken
            
        Case enmInfoRequired
            ctrControl.BorderStyle = fmBorderStyleSingle
            ctrControl.BorderColor = lngcBorderColorBad
            ctrControl.BackColor = lngcInfoRequiredColor
        
        Case enmNoFormat
            ctrControl.ForeColor = lngcFontColorBlack
            ctrControl.BackColor = DefaultBackColor
            ctrControl.BorderColor = lngcBorderColorBad 'Will not appear with no border
            ctrControl.BorderStyle = fmBorderStyleNone
            ctrControl.SpecialEffect = fmSpecialEffectSunken
        
    End Select
    On Error GoTo 0
End Sub

-Joshua
Well, You can try banging your head against the wall, but you just end up with lost-time injuries and damaged equipment. [M. Passman]