Using Audio snap

Hi all,
I am working on a project that has been pre recorded to a basic drum machine beat and has 4 separate guitar and vocal tracks that I have imported so nothing has been recorded on sonar. I am trying to use audio snap to sync everything together so that i can mute the basic drum beat and then create a nice drum track using session drummer.
So I've got the project following the clip but its working out the tempo to exactly half what it should be so when i put the session drummer track on or the metronome its half the speed i want.
I've got everything perfectly in time and the first beat matches the first click of the metronome. 
Where am I going wrong?
I'm using Sonar platinum