Are you following the directions on p. 15 of "http://2010.archive.hobiecat.com/support/pdfs/tigerassy.pdf"?
You probably have figured out which direction to turn the mast when the sail has been hoisted all the way to the top, so will recognize that, contrary to the directions in the above manual, which show the pin on the left side of the luff track, the pin and halyard should be opposite of what is shown in order to line up the pin with the hole by turning the mast rotator bar toward the left; i.e.:
Pin on the right side of the luff track, halyard through from left to right, rotate the mast to the left when the sail reaches the top. That works well for me.
The other key points:
-If the sail is wind-vaning too far toward the left, it will not be possible to rotate the mast sufficiently to line up the pin with the hole.
-When the sail has reached the top, don't let up on the halyard at all before rotating the mast as far as possible toward the left.
-After the step above, pull down on the sail while rotating the mast slowly back toward the right. You should hear a satisfying "ka-chunk" when the pin drops into the hole.