Crouch Walking Etc

I am having trouble animating the crouch walk, when I set it to crouch walk when I crouch(Lctrl) and press W at the same time, what is does is when I press ctrl it goes right into the crouch walk animation but when I am walking but then go into the crouch walk animation by pressing Lctrl and W, but when I let go of W is goes into the default crouch animation. Can someone help me make this more smooth and fix the problem???

I am using the animations from Mixamo BTW.