hmmmm - sounds to me like you're (maybe) not loading the brush with enough "cube." When you add so much water - you need to have a thick enough "slurry" to hold up to shaving.
I don't remember where I read it - but when you think you've got enough suds from the cube: pump the brush up and down on it until if firms up the lather (at least that's what I do).
I also add just a touch of Proraso green or Trumper's Rose to add a little scent to the mix. I have to believe it would help stabilize your mixture, too. Although I'm sure it's stepping out of the bounds of the METHOD.
Screw it - it works for me!
[FONT=Tahoma][COLOR=Blue]Howard L. Sheppard
"I wish I were less awkward around strangers. I never know what to say when someone asks me who I am and what in the world I'm doing in their house." -- Andy Ihnatko