My mmf keeps coming out shiney, am i not using enough powered sugar and if i use too much won't it crack? Can some help me?

are you using a lot of shortening while kneading/rolling it?

Just enough to keep my hands greased

You don't want to keep your hands "greased" you just want to keep the fondant from sticking - use a TINY amount on your hands - not a lot at all.

Thanks i'll try again

the shortening will reabsorb if you let the mmf sit a bit......don't toss it. Once i cover a cake in fondant I grease the whole thing up generously with shortening to get all the corn starch residue off of it.......within a few hours all the shininess goes away!