why when create user in joomla it is not created in cb?

hi.
why when create a user from joomla backend , then in cb not created that user? 
but when user login to joomla from front, then it seems create in cb user managment.

We don't synchronize users on Joomla user creation. Any CB user store, install of CB, or running the user synchronization tool will cause them to synchronize. It's not recommended to use Joomla user management over CBs, but it's not really a problem if you do.

krileon wrote:

We don't synchronize users on Joomla user creation. 

ok i understand that but why? is there any performance or technical issue or it is only remaining from the past?
i'm in developing the custom user registration extension and i want create user in CB. 

ok i understand that but why? is there any performance or technical issue or it is only remaining from the past?

Mainly just due to in the past it wasn't possible. It's doable now, but not a high priority. It's something we'll be improving in CB 3.x. Same with CB Login Module basically. It was created out of necessity, but in a future release you'll be able to just use Joomla's.

i'm in developing the custom user registration extension and i want create user in CB.

I suggest using CB API to do that then.

www.joomlapolis.com/documentation/127-community-builder/279-tutorials/18362-registering-a-user-through-cb-api