VB.NET中屏蔽的文本框问题

我有两个带掩码的文本框，如果它们是有效日期，则会进行验证

下面是两个控件的事件代码

Private Sub txtCutOff_KeyDown(sender As Object, e As System.Windows.Forms.KeyEventArgs) _
  Handles txtCutOff.KeyDown

    If e.KeyCode = Keys.Enter Then

        txtPayPeriod.Focus()
        txtPayPeriod.SelectAll()
    End If
End Sub

Private Sub txtCutOff_Leave(sender As Object, e As System.EventArgs) _
  Handles txtCutOff.Leave

    If isClosing = False And isAddEdit And btnCancel.Focused = False Then

        If txtCutOff.Text.Contains(" ") Or txtCutOff.Text.Length <> 10 Then

            MessageBox.Show("Enter Valid Cut Off Date", _
                            "RMI", _
                            MessageBoxButtons.OK, _
                            MessageBoxIcon.Warning)
            txtCutOff.SelectAll()
            txtCutOff.Focus()

            isField_Empty = True
        Else
            ' Get date details
            get_DateDetails(txtCutOff.Text)

            If IsDate("#" & sMonth & "/" & sDay & "/" & sYear & "#") = False Then
                MessageBox.Show("Enter Valid Cut Off Date", _
                               "RMI", _
                                MessageBoxButtons.OK, _
                                MessageBoxIcon.Warning)
                txtCutOff.SelectAll()
                txtCutOff.Focus()

                isField_Empty = True
            Else
                isField_Empty = False
            End If
        End If
    End If
End Sub

Private Sub txtPayPeriod_KeyDown(sender As Object, e As System.Windows.Forms.KeyEventArgs) _
  Handles txtPayPeriod.KeyDown

    If e.KeyCode = Keys.Enter Then

        txtSewers.Focus()
        txtSewers.SelectAll()
    End If
End Sub

Private Sub txtPayPeriod_Leave(sender As Object, e As System.EventArgs) _
  Handles txtPayPeriod.Leave

    If isClosing = False And isAddEdit And btnCancel.Focused = False Then

        If txtPayPeriod.Text.Contains(" ") Or txtPayPeriod.Text.Length <> 10 Then
            MessageBox.Show("Enter Valid Cut Off Date", _
                            "RMI", _
                            MessageBoxButtons.OK, _
                            MessageBoxIcon.Warning)
            txtPayPeriod.SelectAll()
            txtPayPeriod.Focus()

            isField_Empty = True
        Else
            ' Get date details
            get_DateDetails(txtPayPeriod.Text)

            If IsDate("#" & sMonth & "/" & sDay & "/" & sYear & "#") = False Then
                MessageBox.Show("Enter Valid Cut Off Date", _
                                "RMI", _
                                MessageBoxButtons.OK, _
                                MessageBoxIcon.Warning)
                txtPayPeriod.SelectAll()
                txtPayPeriod.Focus()

                isField_Empty = True
            Else
                isField_Empty = False
            End If
        End If
    End If
End Sub

当我测试有效日期并输入值“1212”时，我按enter键，它会提示用户该日期无效，然后当我再次输入值“1212”时，输出不相同。它删除了我输入的第一个字符，现在的值是“212”

---

当我输入值“1212”并单击其他控件时，没有问题。它将验证日期是否无效，因为它会离开控件并使用Leave事件执行代码，但当我总是按下keydown时，它总是删除我输入的第一个字符。

尝试使用jQuery插件屏蔽日期

Sub get_DateDetails(strDate)

    ' Get month
    sMonth = strDate.Remove(0, 5)
    sMonth = sMonth.Remove(2, 3)

    ' Get day
    sDay = strDate.Remove(0, 8)

    ' Get year
    sYear = strDate.Remove(4, 6)
End Sub