[exim] Filter Piping Problem

OK - having trouble with piping messages from the system filter.

unseen noerror pipe /etc/exim/scripts/test

I'm pretty sure the permissions are right. I can run it from the command
line and it works. Running as user "mail" and I think the error is 127 -
but I do have full paths to everything.

Somehow I think it's "shell" related.

What am I probably doing wrong?