Jay Sean -- 'All Or Nothing' Is More Like Nothing ... For PO'd Producers

Jay Sean's hit album "All or Nothing" didn't happen magically -- so say the music producers who are going to war with Sean's label, Cash Money Records, claiming they were screwed out of a million dollars.

The lawsuit was filed by Orange Factory Music ... which claims it had a deal with Cash Money to produce Sean's huge 2009 single, "Down" -- and seven other songs.

The producers say it took 2 years before they finally saw a check -- for just $211K. They say they continued to get royalty statements for hundreds of thousands of dollars, but never got a check.