Thanks for your reply guys

Yeah the stones reached the green circle above them so I think they were to the required height.

I ll try to load from the last checkpoint and see how I go from there.

After having completed the Cairn Mystery in Sciropecire and have stuck all the stones on top of each other I am unable to validate it and complete it the mystery.

Yet another bug in this game. It makes me wonder if I should purchase The Prince of Persia which comes out in a month...

Considering the awful and despicable job that Ubisoft has done with ac Valhalla I start to doubt it.....