Service Connect - Null Date

I am adding records into Vantage from an excel file and one of the
fields in the excel import is a Date Field. I know for Service
Connect to work, the date has to be in the format yyyy-mm-dd. Some of
my items don't have dates and in the excel file the cell is blank.
Service Connect errors and says that '' is not valid for my date. Any
ideas how to not pass this date?

Thanks