VB.net 數字補0(leading zero)

Dim myInt as Int32 = 9
Dim myString as String = myInt.ToString("D2") // 09
myString = String.Format("{0:000}", myInt) // 009

下面的寫法無效:

Dim myInt as Int32 = 9
Dim myString as String = myInt.ToString()
myString = myString.ToString("D2") // 編譯錯誤
myString = String.Format("{0:00}", myString) // 9