I have Jomsocial 1.8.8 with the extension JomSocial AceSEF 1.5.3
Community Answers 1.1.01 with the extension Community Answers AceSEF 1.5.1

SEO setting in joomla is enable and nothing is working. Please help!

I have Jomsocial 1.8.8 with the extension JomSocial AceSEF 1.5.3
Community Answers 1.1.01 with the extension Community Answers AceSEF 1.5.1

SEO setting in joomla is enable and nothing is working. Please help!

Plz, when describing a problem, always remember to state the versions of software components (AceSEF, Joomla, PHP, MySQL - don't say latest, number plz) you are using (all that may be related to problem).
Also, write maximum information describing the problem, such as full error outputs, behaviour, server type (UNIX/Linux or Windows), SEF & Real URLs, screenshots, confirmation that SEF URLs working as expected using the core Joomla SEF etc. Writing simply "it does not work" does not help much.
www.joomace.net/support/forums?task=misc&page=rules

This is what I have:
Joomla! 1.5.20
PHP 5.2.14
MySQL 5.0
Linux server
JomSocial 1.8.8
Comunity Answers 1.1.01
AceSEF 1.5.4
-ext JomSocial 1.5.3
-ext Comunity Answers 1.5.1

I'm getting this error
500 Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator, support@supportwebsite.com and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.

That is not an extension related error, it's related with your server, check these articles plz:
www.joomace.net/support/docs/acesef/inst...grading/requirements
www.joomace.net/support/docs/acesef/faq/...naming-htaccess-file
www.joomace.net/support/docs/acesef/how-...eliminate-404-errors