Maybe my situation is a bit different but thanks anyway

server:~# su - postgres -c "createlang plperl fred"
createlang: language "plperl" is already installed in database "fred"

on client
-------------
REG-UMAR@192.168.56.6> create_contact CID:ID0001 umar a@b.com 123 KL 55100 MY
Client-side validation command:
xmllint --noout --schema "/usr/local/share/fred-client/schemas/all.xsd" -
Do you really want to send this command to the server? (y/N): y

Client-side validation command:
xmllint --noout --schema "/usr/local/share/fred-client/schemas/all.xsd" -
Return code:              2400
Reason:                   Command failed
 

any more ideas?