Cannot login more than 2 users

I have failed to understand why we cannot login with more than 2 users to RDS. We have been using Terminal CAL licenses on Windows 2008 R2, but now we have purchased 15 CAL per User and installed on Windows 2012 R2 and there are no errors, everything looks good but still we cannot login with more than 2 users. We need this for only Remote desktop, so my question is that when adding Roles, we only chose the "Remote Desktop Licensing" in the features, is this enough ?