I am relatively new to cake decorating and a common occurrence I have come across while icing the cake is the top of the cake sticking to the icing and pulling off. Is there anything that would help this? I am so eager to learn!
Are you crumb coating first? If you crumb coat first you don't need to worry about crumbs getting into the frosting because when that coat sets you'll have a nice clean, smooth cake for your final icing coat. Also, are you waiting long enough for the cake to cool before icing?
Not sure what you are using for icing but sometimes thinning it a little can help with this...HTH.
It might also be that you're not thinning your icing enough. Add some milk or water to it and see if that helps.
I never crumb coat, but I never completely raise my spatula from the cake when icing it. That seems to solve the problem for me.