Grant Date not populated in compensation worksheet via external data

Summary

Stock grant date

Content

I am trying to display following under stock section of total compensation statement

Grant date , Number of shares , Market value of shares

I have loaded above three into external data columns, provided values and mapped it accordingly so as to display in compensation worksheet.

In the compensation plan set up , under user-defined, there are no fields available for date , hence i utilized a text item to map it... which resulted in blank data in compensation worksheet for grant date.

How we can display grant date (of type Date) in external data?