max number of ide controllers?

I have been running with the 2 onboard VIA ide hd controllers (ide 0 and ide 1) along with a creative labs ide contoller on a SB32 soundcard (ide 3). This has had the cdrom and zip drive.

I just added a Promise Ultra100 and it has assumed the role of ide 3 and ide 4. The onboard controllers are still ide 0 and ide 1, but the creative labs controller isnt coming up.

Is there a max number of ide controllers that linux-2.2.18 can support?