To make sure the login is working fine, the JFusion component has an built-in Login Checker that can check the login function among different integrated software packages. The login check can be performed at any time.
Goto: Joomla Administrator → Components → JFusion → Login Checker
Enter the username and password. Press Check Login.
JFusion comes into action as soon as the two plugins, authentication and user, are activated. The corresponding Joomla! ones need to be disabled. You can easily carry out this step by clicking the Enable JFusion Plugins. The Red Cross will turn into a Green Tick if all goes well as shown below.
Sometimes the plugins do not get activated using the method mentioned above on some hosts. In that case you should manually enable the JFusion plugin and disable the Joomla! plugins. Go to the Joomla Plugin Manager and disable Authentication-Joomla! and User-Joomla!. Then enable Authentication-JFusion and User-JFusion.