Set to scan only one frequency

I’m trying to set my radio to scan just one frequency.

So I write down via terminal this command in routeros v.5.26:

[admin@MikroTik] /interface wireless> add frequency=5520 scan-list=5520        
master-interface: wlan1-gateway

but this is what I get:

failure: license level does not allow virtual AP

What does it mean? Am I using a wrong command or do I need level 4 license to achieve this?