Sounds like your terminal settings are being gobbled up. Does it print anything when you strike the "|" key?
It may depend on how you are getting to your Unix OS... If you are using something like Reflections X (from a PC), then the package you are using be be gobbling up the pipe keystokes, and you need to refer to doc from the vendor.
If you are using telnet/rlogin straight on to Unix, then I suspect your term/TERM settings are incorrect.
In either case, messing with these settings can really screw you out of control, so if you have an SA, it might be time to contact him/her.
Hutch