主题：窗体中的控件设置不起作用

我在窗体加载事件中的代码为：

Dim bllb As WinForm.ComboBox = e.Form.Controls("办理类别")
Dim cb As WinForm.ComboBox = e.Form.Controls("村别")
Dim zb As WinForm.TextBox = e.Form.Controls("组别")
Dim yxm As WinForm.TextBox = e.Form.Controls("原姓名")
Dim xxm As WinForm.TextBox = e.Form.Controls("现姓名")
Dim ysfz As WinForm.TextBox = e.Form.Controls("原身份证号码")
Dim xsfz As WinForm.TextBox = e.Form.Controls("现身份证号码")
Dim yzthm As WinForm.TextBox = e.Form.Controls("一折通号码")
If bllb.Value ="挂失补办" Then
    cb.Enabled =False
    zb.Enabled =False
    yxm.Enabled =False
    xxm.Enabled =False
    ysfz.Enabled =False
    xsfz.Enabled =False
    yzthm.Enabled =False
End If

预览后，窗体中的控件仍然可以使用，请问如何修改，谢谢！