Are you using pump up sprayers or electric?
I wrote in another thread last night, I am having trouble getting good results with m/s, did a really bad suite yesterday, tried out m/s and it hardly touched it, had to revert to trad chemicals in the end which lifted it out no bother.
I used a pump up sprayer, One Step @ 10:1 dilution, fine mist spray, which just darkened the material, agitated with soft brush and then extracted with clean water, not clean, repeated whole process without success