Check out the registry value on the CTIOS server for MaxMonitorMode
It should be set to 5 I believe - see below.
See below links.
On the small CTIOS server.
Maximums for Two vCPU Small Agent PG OVAs On this OVA, the numbers of each type of connection are linked. If you use more of one, you can have less of the other. On each Agent PG, you can have the following:
A maximum of seven All-Event clients on the CTI server. A maximum of five monitor-mode connections on the CTI OS server. A combined maximum of nine All-Event clients and monitor-mode connections.