Full error message:

Login name or password is incorrect. [index.php:66 → CWebUser::login() → CAPIObject->login() → CAPIObject->__call() → czbxrpc::call() → czbxrpc::callAPI() → call_user_func() → CUser->login() → CZBXAPI::exception() in /home/zabbix/zabbix-svn/trunk/frontends/php/api/classes/CUser.php:931]