The first cell of the top realtime panel ("N Agents") is computed as follows:

• for each queue, QM looks for all agents that are KNOWN MEMBERS of that queue (that is, they have an association through QM's editor) plus all agents that are logged on dynamically to that queue
• for the grand total (first line) QM looks for all agents that appear in the report - they should match the number of lines of the lowest table

Therefore it is very well possible that the first number does not match the following ones, because on one side an agent can be a known member of more than one queue, and on the other side an agent may not be a known member on any queue (in this case, it will be counted on the grand total but not on a queue-per-queue basis).