stan下载免费:我用VB做了个放大镜，但测试时提示：实时错误'453': 找不到DLL入口点GetDc in user32,请问是怎么回事？

源代码：
Option Explicit
Private Type POINTAPI
x As Long
y As Long
End Type
Const srccopy = &HCC0020
Private Declare Function GetCursorPos Lib "user32" (lpPoint As POINTAPI) As Long
Private Declare Function GetDc Lib "user32" (ByVal hwnd As Long) As Long
Private Declare Function stretchblt Lib "gdi32" (ByVal hdc As Long, ByVal x As Long, ByVal y As Long, ByVal nwidth As Long, ByVal nheight As Long, ByVal hsrcdc As Long, ByVal xsrc As Long, ByVal ysrc As Long, ByVal nsrcwidth As Long, ByVal nsrcheight As Long, ByVal dwrop As Long) As Long
Dim pos As POINTAPI
Private Sub form_load()
Dim usew As Double
Dim useh As Double
usew = Form1.Width / Screen.TwipsPerPixelX
useh = Form1.Height / Screen.TwipsPerPixelX
End Sub
Private Sub start()
Dim sx As Integer
Dim sy As Integer
GetCursorPos pos
sx = IIf(pos.x < 50 Or pos.x > 925, IIf(pos.x < 50, 0, 925), pos.x - 50)
sy = IIf(pos.y < 50 Or pos.y > 680, IIf(pos.y < 50, 0, 680), pos.y - 50)
Caption = "坐标" & sx & "," & sy & "放大镜"
stretchblt hdc, 0, 0, 200, 200, GetDc(0), sx, sy, 100, 100, srccopy
End Sub
Private Sub timer1_timer()
start
End Sub
Private Sub form_dblclick()
Unload Me
End Sub
提示：“stretchblt hdc, 0, 0, 200, 200, GetDc(0), sx, sy, 100, 100, srccopy”这句是黄色的。具体该怎么解决？