กดเลือกพื้นที่ว่างใน datagridview แล้วมันเกิดปัญหาขึ้น เป็นเฉพาะฟอร์มที่มี datetime ใครรู้รบกวนช่วยบอกทีนะครับ

Private Sub dgvPatient_CellMouseUp(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellMouseEventArgs) Handles dgvPatient.CellMouseUp
        If e.RowIndex = -1 Then Exit Sub
        With dgvPatient
            txtPatID.Text = CStr(.Rows.Item(e.RowIndex).Cells("PatID").Value.ToString)
            mskPeoID.Text = CStr(.Rows.Item(e.RowIndex).Cells("PatCard").Value.ToString)
            txtFullName.Text = CStr(.Rows.Item(e.RowIndex).Cells("PatFullName").Value.ToString)
            dtpBirthDay.Value = CDate(.Rows.Item(e.RowIndex).Cells("PatBirthDay").Value.ToString)
            cboBlood.SelectedItem = CStr(.Rows.Item(e.RowIndex).Cells("PatBlood").Value.ToString)
            txtHight.Text = CStr(.Rows.Item(e.RowIndex).Cells("PatHight").Value.ToString)
            txtWeight.Text = CStr(.Rows.Item(e.RowIndex).Cells("PatWeight").Value.ToString)
            txtWork.Text = CStr(.Rows.Item(e.RowIndex).Cells("PatWork").Value.ToString)
            txtFixed.Text = CStr(.Rows.Item(e.RowIndex).Cells("PatFixed").Value.ToString)
            txtLose.Text = CStr(.Rows.Item(e.RowIndex).Cells("PatLose").Value.ToString)
            mskPhone.Text = CStr(.Rows.Item(e.RowIndex).Cells("PatPhone").Value.ToString)
            txtAddress.Text = CStr(.Rows.Item(e.RowIndex).Cells("PatAddress").Value.ToString)
            cboCard.SelectedValue = CStr(.Rows.Item(e.RowIndex).Cells("CardID").Value.ToString)
        End With
        tsAdd.Enabled = False
        tsSave.Enabled = False
        tsEdit.Enabled = True
    End Sub