Your license allows more than 2 users, however RDPlus allows no more than 2 concurrent connections.
1 – Please update your RDPlus to the latest version, reboot the server and try again.
You can get the update here :
http://rdplus.com.au/download/
Make sure no users are logged in before installing this update, you can check for remote users by launching a task manager and clicking on the users tab. Disabling your anti virus is also recommended.
Make a scan exclusion rule on C:\wsession and C:\Program Files (x86)\RDPlus\UserDesktop\files and make sure your users have sufficient rights to read and execute all programs in these folders.
2 – If it still doesn’t work, then it means that a Windows update has impacted the RDP connection module and has overwritten the RDPlus settings.
– open a DOS command prompt as administrator
– navigate to the rdplus\userdesktop\files installation directory (cd “c:\Program Files (x86)\rdplus\UserDesktop\files”)
– run ‘svcac.exe /updatekernel’
– after the popup, open the Windows Services Manager
– open the Wndows Service Manager
– restart the ‘Application Publishing Service (APS)’ service. Two services will also be restarted
After that you should return to normal operation in multi-session mode.