Pltcl can't install on windows

Hello everybody,

When trying to install the pltcl interface, using 'createlang' or the
SQL command 'create language', i get the following message :

ERROR: could not load library "C:/Program
Files/PostgreSQL/8.1/lib/pltcl.dll": Le module spécifié est introuvable.

I use the great Postgresql v8.1.3 on windows 2000. ActiveState Tcl is
installed.

This error message appeared even when I tried to reinstall postgres and
the pltcl interface with the installation program (as described in
http://pginstaller.projects.postgresql.org/)

The file pltcl.dll is in the mentioned directory, and i use the postgres
superuser (named 'alex' on my computer) :

createlang -U alex -d template1 pltcl

The error happens not only when trying to install pltcl on template1 but
also with other databases.

Can someone help me ?

Thanks,
Alexis.