为什么调用ScreenToClient api无效？

VB.NET code

Declare Function GetCursorPos Lib "user32" Alias "GetCursorPos" (ByRef lpPoint As POINTAPI) As Long    Declare Function ScreenToClient Lib "user32 " Alias "ScreenToClient" (ByRef hwnd As Integer, ByRef lpPoint As POINTAPI) As LongDim pi As POINTAPI = New POINTAPI            GetCursorPos(pi)Dim hWnd As Integer = ListView1.Handle.ToInt32            ScreenToClient(hWnd, pi)

ListView1是一个列表控件，GetCursorPos调用成功，ScreenToClient调用后pi的值不变，为什么？

[解决办法]
直接用.net方法即可。
[解决办法]
http://pinvoke.net/default.aspx/user32/ScreenToClient.html