Clone cd problem writing xbox360 game

hello

I recently bought clonecd and have tried to burn one of my game backups

the media i have is silver line DVD+R DL
my OS is windows XP64
and burner is an ASUS DRW 2014L1T

now everythign goes fine but when i want to burn the dvd it says
media not big enough try overburn… while the dvd is supposed to be
big enough 8.5 gig dual layer… i dont know what im doing wrong

if anyone could help that would be greatly appreciated

thanks in advance

How many gig is the game

7.6 gig

someone told me its because my burner is locked, could this be the case, if so, how to unlock it?