I have turn on the SEO setting in joomla, all my pages work but pages with dtregister are giving me 404 error, are there any additional setting that need to be added to enable SEO to work with dtregister component
There should be nothing special to do with core Joomla SEF. However, if you are using a 3rd party SEF extension (like sh404SEF), you must set it to "Skip" or "Ignore" DT Register. You can have SEF urls for the main pages (list, calendar), but the registration process needs to be left alone.
If it's just core Joomla SEF and you're having this issue, first make sure you have the latest version of DT Register in place... then if the issue remains, submit a ticket.