Not being paid commisions and there is no precedent for it

I am a commisioned recruiter. My commision is driven by the amount of Gros Profit (GP) collected by the company. My offical title and signed compensation plan for the company was that of an Account Manger/Market Manager. I am paid purely on the accounts I "own". I had been serving in acapacity as the Dir of Operations for one of our centers while still bearing the above title and compensation plan.
Even though I was responsible for the operations of multiple clients/projects, I have been comped only on those I "own".
In the past at the conclusion of all project(HW/SW installs) if there were associated positives left (excess Gp after paying all consultants and costs)it was credited to me...these amounts were 50% (my portion as the account manager)of the total. These have been 3K and 6K. When there were negatives I was charged 50%...these were 31K, 5K and 3K.
I have now completed my largest project to date and there is $588K in GP left over. By past presedent I am due $294K in GP credit or about $90K in my pocket. I am now beig told that as a result of a project managed by my OPS center that completed negatively (approximately $600K negative)but owned by another account manager, I will not receive the credit for the $588K. I received none of the credit for the negative project as it was ongoing, and the Account Maanager who owns the project is not being held accountable for any of it.

My question is, can my company do this? And if not is there anything short of going to court (which will land me fired or at least extremely in the dog house and never promoted again)that I can do?