Have you seen this ?

How many springs do you have installed in the back of the trem and what string gauge are you using? I'd suggest detuning your guitar until the bridge is parallel with the body of the guitar, and tune up from there. If the bridge is rising up as you bring the guitar to pitch, you need another spring in the back...

Also, check here for trem setup stuff - IbanezRules has loads of info on this sort of stuff and plenty of pics to help you...