shell script error

[Steven Buehler]

I hope this is the right list to ask this on.  I am creating a shell script
for something and the following line (whether run from the script or the
command line) gives me an error:
if [ ! -z /bin/cat /tmp/BACKUP/tmp | /bin/grep 'not accepted' ] ; then echo
hi; else echo no; fi

Gives me the following error
-------------
-bash: [: missing `]'
grep: ]: No such file or directory
no
-------------

If I run the command like the following, it works just fine:
/bin/cat /tmp/BACKUP/tmp | /bin/grep 'not accepted'

Any help would be appreciated.

Thanks
Steve