Was your cake frozen or very cold?
What recipe did you use?
Ditto to what Texas said. I use Indydebi's bc recipe and it crust within minutes (less than 10). One of the many reasons I LOVE her recipe.
If your cake was frozen or very cold when you iced it, the moisture from the cake will prevent your icing from crusting. It will not crust until the cake has come to room temperature. If your fat/sugar ratio is off it may not crust at all...or if too much liquid was added.
recipe???
I used Indydebi's recipie, it was out of the fridge for about 2 hours before I iced it.
Did you have your icing in the fridge at any time? I refrigerated a cake ONCE that I had iced and it took FOREVER to crust. This icing doesn't like the refrigerator 
You said the cake was "out of the fridge for about 2 hours" had it been frozen and maybe wasn't completely thawed? Was it still cold when you iced it? If you used Indydebi's recipe and made it just like the recipe says then it should crust within 10-15 minutes (tops). unless the cake was too cold or was placed back into the fridge after icing.
My icing will crust inside of 5 minutes. I ice one cake .... set it aside. Ice a 2nd cake and by then the first cake is crusted and ready to be Melvira'd.
Logically, when a cake is frozen, the process of putting a cold cake into a warm air kitchen environment will cause condensation to form on the cake. When condensation (water) forms on the icing, then logically the icing won't "dry" as quickly.
The only two times I had issues with my icing was when I put the cake in the refrigerator. Only twice. Never again.
it only had the crumb coat when I put it in the fridge, it was never frozen, I baked it yesterday morning and Iced it after the kids went to bed.
Putting it in the fridge is your problem. Did you use a perishable filling? If not then there is no reason you should be putting your cake in the refrigerator. Crumb coat or final coat of icing...doesn't matter this icing doesn't like being refrigerated. 
Like Indydebi said..the icing crust within 5 minutes. I said 10-15 but she's right it's more like 5 minutes. Wait for your cake to come to room temperature (completely) and try it again. I guarantee you'll get much better results.
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