Feature ID Explanation

Hello,

I am facing wrong Feature installation for a Timer Job - ScopeInvalid. I try to understand the the GUID logic.

I had generated GUID online and put it into my code:

[Guid("8148e9de-2392-4841-8750-b0f7d8d90ce2")]
    public class ContactExport_TimerJob : SPFeatureReceiver

I checked the installation by Feature Admin which shows:

WebApplication: 'ContactExport' [15/97e7189b-4ab3-43ac-bb16-c2974a560bb0]

Finally I checked the table Feature and the column FeatureID which contained none of the mentioned Ids.

How should I understand the logic of IDs?

Thanks a lot,

Radek