userform更改每个控件的背景颜色

Question

我在编写进程以在输入新数据时更改每个控件的背景颜色。当控件为空时，我的代码没有问题。但是当我开始输入值或从组合框中选择值时，它不起作用。此外，该过程对DateTimePicker不起作用。 任何大师能帮助我吗？非常感谢你！

Public Sub Control_Change()
    Dim ctrl As Control
    Dim ans As Long
    For Each ctrl In Me.Controls
        If ctrl.Name <> "cboProjectHealth" Then
            Select Case True
                Case TypeOf ctrl Is MSForms.CheckBox, TypeOf ctrl Is MSForms.OptionButton
                    Select Case ctrl.Value
                        Case True
                            ctrl.BackColor = vbWhite
                        Case Else
                            ctrl.BackColor = vbBlue: ans = ans + 1
                    End Select
                Case TypeOf ctrl Is MSForms.TextBox, TypeOf ctrl Is MSForms.ComboBox
                    Select Case ctrl.Value
                        Case vbNullString
                            ctrl.BackColor = vbBlue: ans = ans + 1
                        Case Else
                            ctrl.BackColor = vbWhite
                    End Select
                 Case TypeOf ctrl Is DTPicker
                    Select Case ctrl.Value
                        Case vbNullString
                            ctrl.CalendarBackColor = vbBlue: ans = ans + 1
                        Case Else
                            ctrl.CalendarBackColor = vbWhite
                    End Select
            End Select
        End If
    Next ctrl
End Sub