You may encounter the error "Birth Date: Please enter a valid date" when trying to enter the DOB on a email signup form on your NetCommunity page which has the NetCommunity and RE7 Web Services Server culture set to Netherlands (nl-NL).
Article
Number:121389
Products:
Blackbaud_NetCommunity_BBNC
We are currently investigating this issue. This page will be updated once the investigation has been concluded.