ช่วยดูให้หน่อยนะคะ งานต้องส่งพรุ่งนี้บ่ายแล้วค่ะ error Conversion from string "0000007DB" to type 'Double' is not valid.

 Private Sub Crebit_ID()
        Dim sql As String = "Select max(Credit_ID) from Credit"
        Dim com As New OleDbCommand(sql, conn)
        Dim max As Integer = com.ExecuteScalar

        If max > 0 Then
            txtCreID.Text = AddPrefix(max + 1, "0", 7) & "CR"
        Else
            txtCreID.Text = "0000001CR"
        End If
    End Sub