stock ssh config problems

[Jack Howarth]

    Is anyone else having trouble getting ssh to tunnel X11-forwarding?
On MacOS X the following works flawlessly...

1) Enable the Remote Login service (ssh) on remote.foo.bar
2) On local.foo.bar execute...

xhost +remote.foo.bar
ssh -X -l username remote.foo.bar

3) once logged into remote.foo.bar via ssh execute...

setenv DISPLAY local.foo.bar:0.0

With those commands I can run xcalc and glgears between two MacOS X
10.4 boxes but these commands do not appear to work from a Fedora Core 4
or RHEL3 box to either Fedora Core 4 or MacOS X 10.4. Any ideas on what
could be going wrong? With linux running xcalc fails with an error of...

Error: Can't open display local.foo.bar:0.0

Thanks in advance for any advice.
              Jack