What do you mean by will not group? Are you saying it will not group your fixed blades with your field points, or when you shoot fixed blades it simply won't group well and when you shoot field points it will?

There is a big difference between the two.

And it's really hard to tell you whats wrong without actually seeing the set up and seeing you shoot.

There are a number of things that could be causing your problems, but the most we could do is just list them all, anything else at this point would just be a guess.

First thing to do is check to see if you have the proper arrows for your set up. Then check to see if the arrows are straight and the tips are square and everything spins true. After that I would look at fletching and FOC. Too little fletching and too low of a FOC makes it difficult to tune broad heads.

After that check to see if your rest and nock set up is good and that you don't have any fletch clearance problems, especially with vanes. An improperly set up rest or nock point can make broad head tuning a real pain. Especially if the spring tension on a prong rest is too high, or if a drop a way doesn't fall at the correct time. And nock low settings can cause all sorts of problems that look like something else when tuning.

Aligning your fletchings with your blades does nothing though, other than it looks cool. It has nothing to do with tuning or performance however.

You might also want to number your arrows and see if the same ones miss all the time. If you get poor or erratic groups, but its the same arrows hitting in the same places every time then you have a problem with your arrows.

Good luck,
Paul