im having the same issue as these guys
http://www.minecraftforum.net/topic/1414484-tekkit-ee-tablet-issue/
In short the tablet menu dosent update when being used
meaning specifically that players cant move items around on the right side
to get to the one they want...
the only way it updates is if you exit the menu and re enter it
however it drops the item in the right center so its not usable
on any level