Why do my animations cancel when I walk?

So I am trying to create a crouch button with custom animations.

When the player hits LeftControl the idle crouch animation should play, when they begin to move the walking crouch animation should then play, and if they stop moving around the idle one will play again.

Though what actually happens when I hit LeftControl is, the player goes into the idle crouch animation, but when I go to move forward they just stand up and start running.

Hope this makes sense, I've probably done something stupid somewhere.