maybe a most trivial question about NAS

I suppose it’s a very trivial and stupid situation, but still: I am trying to start a just installed NAS, and it issues an error “Incorrect function” at startup (I can see it in the Event Log). This error is critical, and the service does not start. I tried this on different machines, and with both Navision Server and MS SQL, the result is the same. First of all I thought that the problem is with the NAS handler function (#99 in the codeunit #1), which as I understand must reside in the database, but it does really reside there. What could be the problem? Help, please.