Hi Herrin,

Welcome to the forum.
Hmmmm, your specific problem sounds like a head scratcher. Could you post the calculation you are doing on the tag?
I remember an OSI TechSupport article that mentioned you could get that error if you are performing non-VSS backups but they plugged that hole in one of the later versions of PI. Otherwise there might be a problem with the archives..? If so, that is certainly one for OSI TechSupport.

Rhys.

Did you get this to work? I would suggest changing the time range of your calculation in line with the dates your archives stop and start, in case of any overlap.

eg. If the calc is from Jan - Feb, but there was an archive shift in the middle of jan, try changing it so it only calculates against one archive file.

If it works in one file and not another then you can probably narrow it down to a problem with a single archive file.

It may be worth reprocessing all archives over the time period of this calculation, as "record header" errors are usually a sign of archive corruption. Has anything changed with the tags recently which may not be reflected in older archives? (range, point type etc?)