Timing Belt walking off

I will try to make this short, I just replaced the cylinder head on my 94 Geo Metro also replaced the timing belt while I was at it (engine at TDC). Before putting the timing cover back on I wanted to make sure I did not need to make anymore adjustments, so I cranked the engine over a few times and rechecked the TDC, everything looked good but I noticed that the timing belt was working it’s way off the camshaft sprocket so I readjusted the belt and turned over the engine a few more times and checked it again the same thing was happing again, the belt was walking off. The belt is tight so any suggestions on what could be causing this will be very helpful.

the lower pulley (damper) keeps the belt from walking out, if you put it on with a bolt ot 2 and turn the engine over the belt should stay where it belongs

Crvett69, I cannot thank you enough for the info; I will try it tonight and let you know what happens. :)

Crvett69, it worked... thanks I should have seen that.. Thank you so much.