[syslog-ng]Expression match problem in filters

Hello, I can't match anything with parenthesis, for use in my filters. I tried escaping, but same result. My filter looks something like: filter f_xpto { match("something") and not match("other(xyz)"); }; I get that "other(xyz)" logged anyway.. "other\(xyz\)" does not work either. Is this an issue with syslog-ng or am i missing something? I'm using syslog-ng 1.5.23. Thanks in advance