Problem in SDS -PAGE - (Jul/24/2006 )

hi all ,
I have run a 12% gel in that i have loded a protein markers ranging from 14KD to 96KD as well as 22KD protein and we found that at 20 KD range the protein present in the markeres and our sample protein is spliting or formini a charring and rest of the bands are oki what could be the reason ?
plz help me
thanks a lot
rajani

you are at the limit of the resolution range.
use a 10% gel