i had this problem alot with my STB, always get enthusiastic with the dmt shuffle and get no solvent on top, once u took soulfood's advice into action and your on your next pull, don't shake your solution! swirl it end to end, roll it around for about 10mins or so and you hopefully wont get the fatty aqueous layer in the middle (I thnk thats what they call it, re-correct me if i am wrong)
that advise was given to me from ''doingkermit'' and always helps!