VB6 - Need help w SendMessage to pass credentials to textbox on another application

[BigWetzticles]

Here is where I'm getting the debug err msg:

Do
    lhndChild = GetWindow(lhndChild, GW_HWNDNEXT) 'Get text of the fist child window
    
    If lhndChild = 0 Then Exit Do 'IF no more child window to ritrive, then exit.
    
    Call GetClassName(lhndChild, StrClass, 255) 'get class name of the first child window
    i = InStr(1, StrClass, Chr$(0)) 'trim the Null Charactors of strClass buffer
    
    If Left$(StrClass, i - 1) = "Edit" Then 'Check weather the contol class name is a TextBox (ThunderRT6TextBox).
       GetWindowRect lhndChild, rec 'Get that windows screen top position.
       strItems(p, 0) = lhndChild 'store the handle in the arrys. <----Here is where the Debug Error pops up at.
           strItems(p, 1) = rec.Top ' Strore the top value in the arry.
       p = p + 1
    End If

Loop