You still need to smooth the fondant when it is applied to your cake.. with your hands or a fondant smoother tool. It looks like a plastic iron you can get it from michaels or your local craft store..this will inturn smooth out your butter cream underneath. I think everyone gets a little bit of "lumps" under the buttercream just smooth them out by gently rubbing them..
thanks, i did use the tool and to come to think of it, the cake was smooth, but afterwords the ici g looked like it was shifting. Or i wondered if my grandaughter was touching the cake while i was gone 
Question: how thick should the icing be underneath the fondant? I appreciated your input 
I dunno bout everyone else but I use a verrrrry thin layer. Like crumb coat. If you get too much bc underneath the fondant and can lookk lumpy.
Elle
If all of these other tricks don't work, try sifting your sugar when you are making your fondant, I have had this problem with MMF, the sugar gets a little bumpy in it. I am not sure if you are using that or store bought, but for store bought, maybe trying rolling the fondant just a touch thicker. I usually put a pretty thick layer of BC underneath, just because it tastes better than the fondant.
either your fondant is too soft or too thin , b/c i had that problem b4 i used toba garretts recipie and tried to make it black and with all the color it became too soft but i put it on the cake anyway andyou could see every shape bump and curve and i also smoothed the cake prior.
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