1996 Ford Probe Problems with timing belt tensioner.

Hi, I am a 2 year automotive technology student working on a 1996 Ford Probe with a 2.0 L engine at school. I had toreplac the head gasket and got it all back together and was getting ready to time it. I put the timing belt tensioner back on and torqued it down to 30 ftlbs. and it won't hold tension. Its the right bolt, the right tensioner, and the right tensioner spring. Is there any reason why it wouldn't hold enough tension? My teachers are even clueless on what is keeping it loose. Please help me, I am getting extremely frustrated with it. Thanx in advance.