Code:
'Force a mouse click by code 

Private Declare Function PostMessage Lib _ 
"user32" Alias "PostMessageA" (ByVal hwnd As Long, _ 
ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) _ 
As Long 

Private Const WM_LBUTTONDOWN = &H201 
Private Const WM_LBUTTONUP = &H202 
Private Const MK_LBUTTON = &H1 

Private Sub Command1_Click() 
'click the Form 
PostMessage Me.hwnd, WM_LBUTTONDOWN, MK_LBUTTON, 0 
PostMessage Me.hwnd, WM_LBUTTONUP, MK_LBUTTON, 0 
End Sub