Unfortunately my application was not Excel. I did however solve the problem:
I Used the Show Window.vi from WINUTIL.llb to get focus on the
Application Window, then used the Delay function in LV 8.0 to wait 0.1
sec, then used the simulate_keyboard.vi to send a return. I lost the
link to it, but this is the improved? version
(http://forums.ni.com/attachments/ni/270/837/1/simulate_keyboard_modified.vi).
Although the dialog box briefly appears and beeps it works good enough
for now.
Andy