im not sure if i have this together right, i have the derailleur hooked in through the quick release axle and the thing seems to be coming loose all the time and my wheel acually fell off once, but there are two holes the is one treaded hole that the derailleur is covering up and there is one to the right on the pic but it looks like a hex wrench would go in it. Any ideas of what the problem might be? Thanks.

