TU3A head gasket troubles

I feel a bit of a dummy on this one- forgive me but I'm lost for ideas.
The engine is a 1.4 TU3A petrol 8 valve 2007.
The job in hand is a routine cam belt and water pump replacement. Head skimmed as a matter of course.
All going back together using a Gates kit. Correct fitment has been checked.

The problem- is as if the belt was too long. But it isn't- exactly the same as the old one and with the same tooth count.
The crank sprocket has not been moved. The head was sent bare for skimming, then everything refitted with no changes apart from a cam oil seal.
The Gates water pump and tensioner are identical to the originals.

So how in the world can the tensioner be turned through 360 degrees without applying any tension to the belt?
I would really appreciate any thoughts.

Check the numbers on the belt. The kit number might be right but the belt number might be wrong.

I have a blurb here on changing the belt (if you haven't already seen it):
tips-for-a-petrol-powered-c3-f7/how-to- ... t3868.html

Compare how you did it to how I did it. Pay particular attention to the part with the timing marks on the belt! If the marks don't line up, it's the wrong belt!

It sounds like everything is right so it just has to be a fundamental thing you are doing wrong.

I have a favorite saying, "first the gunpowder, then the wadding!".
https://www.youtube.com/watch?v=T9s2ayNU204

It's a convoluted "in-joke" but the crux is that you tend to over look the VERY OBVIOUS things.

Many thanks for your help, and the link to your excellent tutorial.
It helped me to retrace my steps- and discover that nothing was wrong! I had not realised with the transit pin in place on the tensioner the thing was capable of rotating through 360 degrees without touching the belt.
This was compounded with an incorrect Haynes manual instruction to locate the tensioner on a non existent casting pin.
I then went on to over think the whole thing and was starting to consider that the head had been over machined!