Widget Animation greyed out?

For some reason I could access the Animation keys after I deleted my ‘MenuFlyIn’ and ‘MenuFlyOut’.

I try creating another of the same name and it refused saying that ‘An animation of this already exist’.

I created a new one called GameMenuFlyIn and I was able to access the keyframes.

28878-ue4debug2.jpg

Why do I have to delete first and create a new one to access the animation keyframe?