Wincc V6.0 Alarm Logging - Tag out of an existing DB

Dear Sirs,
I'm developing a new WinCC project with version v6.0 sp3.
I see that if I configure in alarm logging one alarm on a tag (es.DB10.DBX100.0) and the DB10 in the PLC is little than 100 bytes, the wincc doesn't read any tag from the PLC. All the tags will have quality code = 8. If I disable the Alarm Logging the WinCC read all the tags. If I cancel the alarm of the tag out of the existing db the wincc work correctly.
If the alarm is configured on a tag of a DB not existing the WinCC works correctly, no problems for other tags, but with one alarm on a tag that is out of an existing db the WinCC doesn't read any tag of the project.
I see that with WinCC v6.2 SP2 it happens the same .......
Can somebody tell me why this happens? Am I in mistake ???

Thanks

The support confirm me that this is a normal behaviour of WinCC