Problem with GetPixel - help please

The routine I have below I want to get the pixel of the screen. It returns nothing here. If I move the GetPixel call out of the loop, it returns something.

Any idea what I'm doing wrong or a better way of this?

Thanks!

VB Code:

Private Sub Command1_Click()
Dim hDC As Long
Dim H1 As Long
Dim W1 As Long
Dim Z As Long
  H1 = Screen.Height / Screen.TwipsPerPixelY
  W1 = Screen.Width / Screen.TwipsPerPixelX
  Dim X As Long
  Dim Y As Long
  hDC = GetDC(0) 'get desktop dc
  
  For Y = 1 To Y1 - 10
    For X = 1 To H1 - 10
      
      Z = GetPixel(hDC, X, Y)
      Memo1.Text = Memo1.Text & Trim(Str(Z))
      
    Next X
  Next Y
 
End Sub

you're using Y1 rather than W1 (or whatever it should be) in the first For - use Option Explicit at the top of the form to catch these errors!

Also, when using GetDC(), you need to use ReleaseDC() when you're done with the DC. That allows the DC to be used again.

VB Code:

Declare Function ReleaseDC Lib "user32" (ByVal hwnd As Long, ByVal hdc As Long) As Long
 
'ex. in your sub, when you're done with the DC
Call ReleaseDC(Me.hwnd, hdc)