Ok, everything seems to be working fine now, and it's all thanks to BYTEmySITE! :D
There must have been some problem with the way I added the first operator+assignment. What I did was follow BYTEmySITE's instructions (sent via email):
1. Select: System Configuration
2. Select: Operators
3. Select: Add (operator) complete and save
4. Select: Assignments
5. Checkbox: User Name, enter priority to take requests
1-9 for example, then select EDIT.
So I added a new operator with those instructions and tested by chatting with myself.

Thank you very much for your help, BYTEmySITE!
Rgds. :)