User tab error 404

I followed all Moodle and Joomdle instructions to integrate Moodle with my Joomla 2.5.20

All seems to have gone well except the user part.

When I click on the Users tab in the Joomdle component, I get this error: XML-RPC Error (404): Unknown error

When I run a system check, everything is good except:

Joomdle Web Services An unexpected error happened: 404: Unknown error

Any ideas what is wrong?

When I enable dubugging in Moodle and try to go to the user page in Joomdle, I get this error:

XML-RPC Error (23000021): Access control exception | DEBUG INFO: You are not allowed to use the {$a} protocol (missing capability: webservice/xmlrpc:use) | ERRORCODE: accessexception

It seems you did not add xmlrpc capability to the web services role.

in joomdle component appears when I click Users
XML-RPC Error (404): Unknown error
searched the forum and not found SOLUTION
the problem happened when I imported users
checked the configurations and they are all oks
Users have to 'and the ~ username, can this be?

joomla 3.3 r095

how you solved the problem?
XML-RPC Error (404): Unknown error
searched the forum and not found SOLUTION
the problem happened when I imported users
checked the configurations and they are all oks
Users have to 'and the ~ username, can this be?

joomla 3.3

Yes, ' and ~ may be causing problems.

Try removing those users, and test.