Problem with SPDiagnosticsService

Hi, I am using SPDiagnosticsService in farm like this:

SPDiagnosticsService.Local.WriteTrace(0, new SPDiagnosticsCategory("CustomLog1", TraceSeverity.Unexpected, EventSeverity.Error), TraceSeverity.Unexpected,"test", "test1");

Unfortunatelly this line throws error "Object reference not set to an instance of an object".

I am using this in development (standalone) solution and it works fine, but when I passed solution into farm I've got this error as above.

I also checked and SPTraceV4 service is running and it's running under Local Service on each front end.

Thanx for any help.