Q:How could I see why a program doesn't launch from menu ?

[Animateur cyber de Saint-Thonan (Stéphane Ascoët)]

Hello,
I've put a game (Puzzle blocks) in a XFCE menu. When I paste the 
command line in a terminal (under the same user of course), the game 
works. When I click on it in the menu : not ! :-( It's XFCE 3 under 
Freeduc (based upon KNOPPIX/Debian). This entry is the last one the 
menu can handle (no more room in the menu). I've added it using "add to 
menu...".
Is there a log or something where I could find what's the problem ? 
Thank you for advices (but don't tell me : use XFCE 4 ;-)  ) .
-- 
Mail, Camino & AW6.2.9 under eMac OS X.2.8 (viruses ? what's that ? :-) 
)
Sincerely, Stephane  http://stephaneascoet.ifrance.com