When you say it didn't work, what did it do? What did it not Do? Are all of the dates the same format as 2001/3/14?
I thought these records already existed?
The calculation does work. The import of the 80,000 records does work. What does not work is this date field while bringing in these 80,000 records. I think that is because there are about 20 records that have nothing in this date field.
Would that stop the entire column from coming in?