substring function

Being new to PGNP I might be doing something wrong or misunderstand the way PGNP can be used.
After having successfully connected to a remote PostgreSQL DB and run several queries via PGNP I went for something a bit more complex.

It appears, though, as if when I used a substring function (regex), the provider failed to interpret the query and didn't return any data. The very same query works without any problem in the PostgreSQL query tool.

Query example:
SELECT cid, CAST(SUBSTRING(full_domain_name FROM '^(/.+)[/]|(/)') AS varchar) AS "domain_name", client_name, client_addr, os_type, agent_version FROM v_clients_2;

When I remove the column with the substring function from the query everything works nicely.

Is that a limitation of the trial version or are such string modification functions not supported?

Many thanks for shedding some light onto this.

Raphael

After some more experimenting I found that by using a different syntax the query works fine. When not using the documented form from [url:aa94lq58]http://www.postgresql.org/docs/8.2/static/functions-matching.html[/url:aa94lq58]
--> substring('foobar' from 'o.b')
but
--> substring('foobar', 'o.b')
the provider does forward the query to the db server nicely.