Hi,
Indeed, it looks like the search override has no effect there. Well, that could happen for a number of reasons.
Do you have any other search plugin active by any chance? If so, that could explain it, as it could override the results that this one tries to pass to the results page.
If not, then there is a chance that the theme might have a separate search method active within the code. In that case, I might need FTP access to try to debug it.