Maxi Taxi

i made a small song in cakewalk. it consisted of spitfire labs drums, a bass and 2 guitars recorded through a behringer um2 audio interface. i saved my project, but when i opened it again, you couldnt hear the bass and the guitar. the tracks were there, but no audio. i checked the input devices and they were configured right. i used the th3 plugin (the amp one) for both guitars and bass. i hope someone will help me fix this problem. - maxi taxi