Could be either one.

Check the following problems:

1. Left elbowtoo straight. Caused by trying to extend the bow out or gripping too tightlyinstead of just holding it loosely in your hand.
2. Right foot is not directly behind left foot. Try a more closed stance.
3. Left shoulder pushed up. Shoulder gets pushed in from too much draw weight.

I usually hit mine if I break 1 or 2.