incorrect tag for option indexValue.yearOnly

[winxi]

Hi,

I separate between the release date and the original release date of an album with the entries 'Date' and 'OriginalDate' in the indexTags property.
When applying the indexValue.yearOnly tag option to Date, it works fine. However, when applying it to OriginalDate, I get a red icon with the following message:
MinimServer: incorrect tag 'OriginalDate' for option 'indexValue.yearOnly' in property 'tagOptions'

Is the indexValue.yearOnly option valid for the Date tag only?