mecanim stuck

Hi all, I have been working on fps project recently and in have run into an issue in the animator. The animation work fine until I try firing the gun too quickly at which point the shoot animation freezes on the last frame and wont transition out of shoot. I have included the relevant portions of my code.

if (Input.GetButtonDown("Fire1")) { animator.SetBool("fire", true); }

public void off() //activated by event in animation { animator.SetBool("fire",false); }