[@serimu Member 17 years ago]

I changes ifmodule to IfModule but it did not fixed the problem. And I dont know why it is lowercase for my .htaccess file. It may reason from a previous bbpress rewrite-rules.php or not. I dont know, and I also could not figure out that difference.

I also tried to rename wordpress’ .htaccess file to check whether it creates a problem or not. When I do that, I get my website working for root and all wordpress pages are not reachable. Forum is the same. So I get an idea, is there any problem with the server or apache for reading the .htaccess file located on /forum folder. Is there any option on apache, or somewhere on the server to read or not to read the .htaccess files on subfolders?

And I contacted to technical stuff of hosting company, and he asked for the apache version where I was using my site with no problem. It was Apache 1.3 , and this vps has Apache 2. So he said he will try it with apache 1.3 to check whether it is working or not.

UPDATE: I added a rewrite rule to .htaccess file on /forum folder to check whether it works for a simple redirect or not. And it worked for:

Redirect /forum/a/ http://www.domain.com/b/