Timing belt (again)

[Dieselumbrado]

Today I tried to put back the timing belt, that I partially removed when replacing the HG.
I did what the pros told me, I removed the camshaft sprocket and put back along with the belt.
The problem is that still a tight fit, even with tensioner slacked,  everytime I put the belt, the mark on the flywheel moves.
I don't know if I have to unlock the IP, but I'm afraid to disturb it.
Maybe I'm overlooking something, any suggestion is welcome and appreciated.

Thanks

[burn_your_money]

Does putting it in gear help? I've never tried it before so I'm just speculating.