I am assumig terminal services. If so, is your terminal services configuration set to “Per Device” or “Per User”?
If it is per device, than termial services forces licening and will not let more devices connect than you have licenses. Check to to see if your TS configurationis Per Device and then check to see if you have enough licenses installed in terminal service licensing to account for the number of connections.
If you set TS configuration to Per User, than TS will not force liceniing.