vba excel - Parental control multipage userform runtime error 438

If I were you I would write three branches of code.
1) to deal with a text box on a MultiPages' Page
2) to deal with a textbox in a frame.
3) to deal with a textbox on the UF, outside of a frame or a MultiPage.

Something like

If Type(Ctrl) = "TextBox" Then
    Select Case TypeName(Ctrl.Parent)
        Case "Page"
            ' your current code
        Case "Frame"
            ' what do you want to do in this case
        Case Else
            ' more code
    End Select
End If