Issue with modding weapons need help plz

I've just started modding borderlands and i'm useing a flash pen to transfer the files and USB Xtaf Xplorer to get the save from the pen and willow tree beta 10r13. i'm perfectly fine when it comes to changing bag space, money, skill point item drops and makeing the odd working weapon. My Problem comes when i'm trying to make a powerful gun i put all the parts in the right place and even made one out of all the brand atlas semi-auto sniper but when i load the game up on my xbox 360 the gun is nowhere to be seen i have the lastest patchs and all new DLC's and have tryed looking everywhere for a hint i even tryed making an invisble weapon that just did the same so if anyone can advise me on how to resolve this problem it would be alot of help. i'm not looking for someone to give me weapons because i would like to know how to make them myself. i had tryed looking at the builds of my mates modded weapons but they did not appear on willowtree.