2008 gti 2.0 new timing belt broke
 

Me and my brother bought a 2008 volkswagen gti 2.0 that didnt run. Took engine apart and istalled new timing belt, new tensioner, valves , new timing chain and tensioner. We got car running drove it around block a few times before we insured it. My brother used car today and new timing belt broke. Anyone have any ideas why this would of happened? We done valves and timing chain on all our audis so i dont know what happened we also chained all the rocker arms and lifters