Help: ReadProcessMemory

I was wondering if anyone can help with my problem. I am writing a program that will read the virtual address space of another process. My problem is in the ReadProcessMemory API. For some reason I keep getting a null value. Before I start my "big" program, I figured I'd try it out on a small one, so here's what I've done so far:

- Open the windows Calculator
- Enter a number in the window (ex. 33557799)
- I used SoftIce to determine the address location of that string (ex. H809D3E00) to be used for the API
- Then I plug that into my program
- 1 Form
- 1 TextBox
- 1 Button

-- General declarations --
Private Declare Function FindWindow ...
Private Declare Function GetWindowThreadProcessId ...
Private Declare Function OpenProcess ...
Private Declare Function ReadProcessMemory ...
Private Declare Function CloseHandle ...


Private Sub btnReadText_Click()
Dim hwnd As Long
Dim pid As Long
Dim pHandle As Long
Dim str As String * 20

hwnd = FindWindow(vbNullString, "Calculator")
If (hwnd = 0) Then Exit Sub

GetWindowThreadProcessId hwnd, pid

pHandle = OpenProcess(PROCESS_ALL_ACCESS, False, pid)
If (pHandle = 0) Then Exit Sub

ReadProcessMemory pHandle, &H809D3E00, str, 8, 0&

txtDisplay = str

CloseHandle hProcess

End Sub


Now when I run the program and click the button, the text box is empty although it SHOULD display the same data as the Calculator. I'm stumped as to what i'm doing wrong.