OPTION不能赋值给text.box

VB6中，类模块代码
Option Explicit

Private WithEvents cFrame As MSForms.Frame
Private WithEvents cOption As MSForms.OptionButton
Private WithEvents cTextBox As MSForms.TextBox

Public Sub Attach(f As MSForms.Frame, p As MSForms.OptionButton, t As MSForms.TextBox)
Set cFrame = f
Set cOption = p
Set cTextBox = t
End Sub

Public Event OptionButtonClicked()

Private Sub cOption_Click()
cFrame.Tag = cOption.Caption
RaiseEvent OptionButtonClicked
End Sub

窗体代码
Option Explicit

Dim cls() As New 类1

Private Sub CommandButton3_Click()
Unload Me
主页胸部肿瘤.Show
End Sub

Private Sub CommandButton35_Click()
Unload Me
主页恶性肿瘤分期.Show
End Sub

Private Sub TextBox100_Change()
Dim Mystr As String
Mystr = CStr(Frame1.Tag) & CStr(Frame2.Tag) & CStr(Frame3.Tag)
TextBox100.Text = Mystr
Select Case Mystr
Case "T1aN1M0"
TextBox200.Text = "IIB期（AJCC第8版）"
Case "T1aN2M0"
TextBox200.Text = "IIIA期（AJCC第8版）"
Case Else
TextBox200.Text = "?"
End Select
Dim Mystr2 As String
Mystr2 = CStr(Frame3.Tag)
TextBox100.Text = CStr(Frame1.Tag) & CStr(Frame2.Tag) & Mystr2
Select Case Mystr2
Case "M1a"
TextBox200.Text = "IVA期（AJCC第8版）"
Case "M1b"
TextBox200.Text = "IVA期（AJCC第8版）"
End Select
End Sub

Private Sub Me_Initialize()
Dim ctl As Control, c As Control, N%
For Each ctl In Me.Controls
If TypeName(ctl) = "Frame" Then
For Each c In ctl.Controls
If TypeName(c) = "OptionButton" Then
N = N + 1: ReDim Preserve cls(1 To N)
cls(N).Attach ctl, c, TextBox100
End If
Next
End If
Next
End Sub

Private Sub OptionButton_Clicked()
cFrame.Tag = cOption.Caption
cTextBox.Text = TextBox100.Text & cFrame.Tag & cOption.Caption
RaiseEvent OptionButtonClicked
End Sub
运行后Option.Caption不能赋值给TextBox100，不知道哪里出的问题，代码如何修改？

注释掉所有On Error Resume Next语句，在VB IDE中运行，
出错后点击调试，光标会停在出错的那条语句处，
或者
事先在怀疑可能有逻辑错误的语句处设置断点，运行经过断点时中断，

此时可以在立即窗口中使用
?变量名
或
?函数名(函数参数)
或
过程名(参数)
辅助调试。