Headache with a plpgsql function

I use pgmanager from EMS to code, and have a fucntion that is always returning a NULL value, when I run it in debug mode it works fine, I've traced the problem down to this line

tag := substring(s, '<\s*?[^>]+\s*?>');

are there issues the regexps? I am using - PostgreSQL 8.0.3 on i686-pc-linux-gnu, compiled by GCC gcc (GCC) 4.0.2 20050901 (prerelease) (SUSE Linux)

Dean