[Closed] Render Save a black image

Hello,
i was trying to save the last rendered image but everytime i get a black image
this is the code i’m using

autosaveimg = getLastrenderedImage copy:off; 
rendSaveFile =true; 
autosaveimg.filename ="cmon.jpg";  
save autosaveimg;

i was searching google for 4 hours and i still can’t get why this is happening :banghead:
can anyone help pls?