各位大佬vb.net中出现graphics.fromhdc（hdc）hdc的值为空，怎么解决？

vb.net中 Dim G1 As Graphics = Graphics.FromHdc（hdc）调试时出现hdc值为空的现象

Private Shared Function CreateDC(ByVal lpszDriver As String, ByVal lpszDevice As String, ByVal lpszOutput As String, ByVal lpInitData As IntPtr) As IntPtr
End Function
    Dim capture1 As IntPtr = CreateDC("DISPLAY", Nothing, Nothing, Nothing)
    Dim get1 As Graphics = Graphics.FromHdc(capture1)

向各位大佬请教