adding additional serial ports
 

Hi!
I am running RedHat 6.0 (2.2.12 kernel with realtime extensions). Yes, I know it's old! Computer is AMD Athlon running at 1500 Mhz with 128 megs of Ram.
I installed a Startech PCI Serial/Parallel card, Model PCI2S2P, (2 parallel, 2 serial ports.) I got the parallel ports working fine, the serial ports are another story.
I have 1 serial port built into the motherboard, working fine as ttyS0. I used setserial to set the others. I got the addresses and IRQs from the /proc/pci listing and am pretty sure I got them right because when I write to the port I'm able to send and recieve data, but it's only garbage, not the data I sent.
Do I need to change the speed or parity? I've been playing around with everything it seems, but no luck!
Any help is appreciated,
Lorne