HELP!! The last 2 cakes I have done I have gotten a big (about the size of a quarter) bubble under my bc the next day. It pokes it out and makes it crack. I can push it back in but it leaves a mark. What am I doing wrong?

Many think its because the cake was not given time to 'settle' and develops gas. I cannot go along with that because I have iced many a cake right from the cooling rack & not had bubbles.

*Most likely* it is because you did not attach the icing well enough to the cake. This is done by smoothing well with a little pressure.
What size was the cake? I bet it was a small round - like 6" or smaller? That is usually where the problem comes in. Those little one tend to scoot when you apply icing with any amount of pressure. Put a non-skid rubber piece under the board to keep it still.

There was a really good thread going on this exact subject not too long ago. It gave lots of differnt ideas and suggestions on how to fix it. I'll see if I can find it and post the link.

Here it is, hope this helps!

http://cakecentral.com/cake-decorating-ftopict-731220.html

THANK you SO much!!! This really helps!!

I have found that when this happens to one of my cakes, is when the cake is still damp on the outside,, meaing if i had it covered in plastic,, i did not allow enough time for the cake to dry a bit,, when it is left damp the icing cannot stick to the cake,, it has no support,,, it would be like trying to keep icing on a icecube,, if you freeze your cakes and then ice your cakes,,this will happen to it also,, because the cakes may not be dry on the outside,,,if you also use non-saturated shortening in your icing,, this can sometimes do it too,,, if you ice your cakes then allow them to sit for 2 or 3 days, the icing will pull away (form a bubble),,, also when you have your cake sitting in your car, and the sun is beaming in on it,, it will create a hot spot and this can make the icing bubble too,, my key advice is to allow the cake to dry a bit before you ice it at all,,, hope this might help ya out..