installing pgtclu

I hate to ask such a lame question but I've got an error I just can't
solve.

[postgres@yojo postgresql-7.1.3]$ createlang pltclu monitoring
ERROR:  Load of file /usr/local/pgsql/lib/pltcl.so failed: libtcl8.3.so:
cannot open shared object file: No such file or directory
createlang: language installation failed

tcl is installed and working.  I've set every environment variable I can
think of.  The tcl libraries are installed into /usr/local/lib and were
compiled as shard libraries.  Why can't createlang find libtcl8.3.so?
I've been searching newsgroup archives for an hour and surprisingly
can't find the answer to this one.

Thanks,
Fran