E-99 won't fire

[aadepa]

Ive got an e-99 i bought new, but was only about to use 3 or 4 times. I tried using it the other day with a full tank and fully-charged battery but it didnt fire. When the trigger is pulled it makes a little click but nothing happens. I brought it to my local paintball place and they held it for over a month without looking at it because they wanted me to buy a new gun, and then had the nerve to try and charge me when they didnt do anything to it. So any help is appreciated.