[CentOS] 2 machines running centos and parallel ports

I have two machines both running centos 4.3.
I have a laplink cable (parallel) between them.
On one machine I do "echo Hello > /dev/parport0"
on the other machine I wrote a short c program to open /dev/parport0
and when characters arrive print them on the screen.
Seems simple enough but nothing comes across.
Both machines parallel ports are set for PS/2 mode.

Is there a reason this would not work?

THanks,

jerry