Fitted a new fabric hood... Big problems!

Soo, I've fitted a new fabric hood from "softtopsonline" followed a very detailed how to from a fellow 355 owner here in the UK, lined it all up perfectly with the front screen and windows, then fastened the back supporting bolts up along the rear wings (fenders). It all looked fine, then all of a sudden it went so out of line after a couple of cycles, and has bent the back bow (that goes from side to side, and above the back window)
I straightened it all out with a jack, hammers and dollys, and some gentle persuasion.. I reached the conclusion that the rams may of been gummy, so bled it (was pretty thick and glupy) after quite a few cycles and adjustment the frame closed all the way and operated better than ever!
Fitted it all up (very chuffed and excited) and after a few cycles it bent the rear bow again! It Lmost seems as if the canvas is too small at the back! Any help would be greatly appreciated guys!

http://www.ferrarichat.com/forum/technical-q/316148-procedure-cure-355-spider-roof-does-not-close-properly-due-old-fluid-2.html#post143182598

 

Come on my "soft top gurus" help me out...