Java 64bit not allocating memory in all mod packs including vinilla

[DanNyyy]

Hello i am having issues allocating memory to attack of the B team and everything else for that matter i have tried everything i have done the  run time pentameters and yet my max memory allocated is 499mb when i allocate 3 GB and just sits at 399mb and have no idea how to fix it i have 8 gigs of ram and the latest version of java and have even went back versions of java any help would be greatly appreciated 

 

Screen shot : http://puu.sh/gxs63/88af8c72b2.jpg