Indexing Service and regex

[Mr. Tomaszek]

Hi All,
I have problem while querying indexing service. I can run query using regular expression like this

{prop name=filename}{regex}|[0-9].doc{/regex}

But it looks like it doesn’t work while trying use redex on contents fo files which is exactly what I wan to do. Search for files that contains given pattern
Even something as simple as

{prop name=Contents}{regex}.*{/regex}

Doesn’t work.
Any ideas how can I run search for given pattern inside files? Any suggestions are welcome.