I'll hazard a guess that you have not regulated the collision object(s) for your player. There are two easy ways of doing this in C2.
1) Create a transparent rectangular sprite the ssame size as your player assign the pin behaviour then pin the player animation to this invisible rectangle. From then o you want your collisions tocoinide with hittingthis collision detector NOT the player which will probably not be a uniform shape.
2) In the C2 image editor set the collision boundaries to a rectangle and apply throughout all animations.
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