RAM doesn't work. Urgent

[AndreiArgeanu]

Hi. I tried to upgrade my buddys pc. He has an i3, 2gb 1333 ddr3 mhz of kingston ram, 380w antec 80+ bronze power supply and a p7h55-m motherboard. I think the new stick is clocked at 1333mhz and its transcend 2gb. I tried to add 2gb to the dimm slots marked b2 the other stick was in b1.After adding the ram the pc didn't post with no beeps. Tried to put the new stick of the ram to the slots a1 and a2 but it was booting up showing 2gb. Moving both to slots a1 and a2 would end up with one medium beep and two short one's which I suppsose means no ram. Swapping the working ram with the new ram worked just fine, the pc booted up. I need help quick, how do I make both sticks work? 

[AndreiArgeanu]

It also has an expansion card which has one firewire port and 2 ports which i dont what are they.