I made a chocolate cake and iced it with chocolate ganache and then wanted to add a layer of fudge frosting. But when I poured the fudge frosting on the ganache covered cake it just fell of the cake and pooled around it in clumps?!!

This is very tricky to do. The ganache needs to be chilled and the fudge frosting needs to be only lukewarm. What happened is that your ganache melted under the frosting.
Problematic can be even the outside temperature - you need to work very quickly and try to get both back to cooled stage as soon as you can.