hi all... i used to make icing according to directions in a wilton book but could never get my icing smooth.....so then a friend told me she gets her icing smooth by #1 not using crisco..using butter only and a very very small amount of milk and making sure its not too dry but dry enough so that when you touch it after about 10 seconds that it does not stick to your finger and #2 by smoothing it out with a vive paper towel and a fondant smoother.... so this is working much better for me in general....but all of a sudden i am having major icing issues.... i am scared to make a cake now because the last 5 cakes i've done have all had issues of the icing cracking and/or pulling away from the cake in chunks and/or getting this look like it is shrinking into the cake.... can anyone tell me why???? is it because i'm in texas and its been a million degrees everyday all summer??? or is it that i am not using enough butter to the amount of sugar maybe so that when it completely dries it is just TOO dry??? please help! major cake order for next weekend and idk what to do. tia!

Not smooth meaning lumps?