of the compression stroke (only happens once every 2 revolutions of crank at the timing mark at the crank damper) and have the crank damper mark lined up with the stationary mark on block. If all ok the 4 cam pulleys will line up with their respective stationary marks on the heads. In 4 cycle engines the cams rotate 1/2 a revolution when the crank rotates 1 revolution so to be at TDC for #1 at compression stroke is the key here. Once all marks are lined up then RECOUNT the number of cogs on the belt between marks as noted in the factory manual. Have you rechecked the tensioner clearance?
The marks on the belt are for the initial install to get the correct number of cogs between the pulleys. Just a reference, still need to count the cogs to be sure. Rotating the engine will make the lines on the belt not align until a huge number of revs as Cjw3 states.