sql listen fails using libpgtcl

Hi there
 I don't know too much about either TCL or Postgres, so this might be a
really silly thing. Anyways. We've got a TCL script interfacing against a
(remote) PG server using libpgtcl. I've got to move that script to another
machine, where I've installed libpgtcl doing "apt-get install libpgtcl". 
 Everything works (can connect to the remove db and do a few select
statements), but where the script attempts a "sql listen <tablename>
<notification>" statement I get a run-time error:"bad option 'listen': should be one of     sql cget -option    sql
commit   [etc]"
 
 The Postgres server is 7.2.1 on debian linux. 
 On the machine where the script is working, the libpgtcl's debian package
gives its version as 7.2.1-2woody4; where it's not working the version is
7.2.1-2woody8, if that is of help at all. 
 Any ideas on what this could be? Thanks.