Ok I want my buttercream to crust but never before has this happened! Did me cake for Womens Day for a client. I loved the look, even got the silver written to work out and my flowers I think look great. The next morning the buttercream had crusted to much! So many lines and cracks in the frosting! It was smooth out and looked perfect last night. I did the best I could to make it look better but I was ashamed when she came to pick it up. What could have gone wrong? Someone please help me, I have another cake due tomorrow and I really don't want this to happen again.

What makes an icing crust is less fat than sugar. So add a bit more fat (shortening or butter) to it.
Not knowing exactly the recipe you used I cannot say for sure who much more but here is a great icing recipe to use:
http://cakecentral.com/recipe/2-icing

Be sure to read through the whole recipe and comments for helpful information.
One other thing: did you move or pick up the cake - especially more than once? If the board you have the cake on is not sturdy enough it can cause the cake & icing to flex, causing cracking.

Thank you so much for the recipe and the reasoning of what might be going on. It is so helpful and very much apprieciated. I will try this and let you know how I do.