I have a d.g.v. with two columns. One is set as date and the other is set as decimal. If there is a row and a number is typed in the decimal column, you can delete it and leave the cell empty. However, the program will not let me delete the contents of a date cell and leave it empty. It just gives me the default error dialog saying that I need to put the contents in proper date form and it doesn't let me leave it blank.

How can I make it so that it allows me to leave the cell blank?