The sail strongly looks as if its not fully raised - the boom aft end seems lower than the tack, it has an immense amount of draft, draft seems to be too far aft, and the head of sail is not near the 'black band' at the top of the mast.
Dacron (not on in-mast furlers)
mainsails with luff boltropes NEED to be stretched out along the luff via halyard tension so that they take their as-designed shape.
That big diagonal crease, and all those little creases along the luff are indicating that the halyard tension wasnt set correctly
after you raised the sail. "Girts" or creases that are observed are usually a symptom that one or more 'corners' of a sail are improperly tensioned - in this case its probably two corners (improper halyard tension). Dacron is 'stretchy' and you need to properly tension all 'corners' when raising. If it would be that there is too much mainsheet tension, that big 'girt' would be pointing more towards the head of the sail; so, my suspicion is a too slack luff/halyard.
Here's how to PROPERLY raise a woven dacron mainsail and how to
precisely adjust that needed halyard tension:
http://forums.sbo.sailboatowners.com/showthread.php?t=120970 see post #1 in that thread.