check to make sure your on #1 plug
check on a bone stock something and see if its where its supposed to be
try another timing light
for where ever reason timing lights are very troubling and can cause all kinda of head aches...
also just a quickie pull number one plug, rotate motor to TDC compression (stick a thin dowel in and wait for the stick to stop moving). then check the balancer to make sure its at 0* TDC and see where the rotor in the distributor is in relation to tower number one.