Hi @LinaJ2020 .
Indeed, leaving the entry blank prevents the Error. I was going back through the Interview to see the exact wording of the instructions:
If Schedule D, Line 15 is a gain, enter the amount on this line.
If Schedule D, Line 15 is a loss, do not enter an amount on this line and leave the line blank.
So, I was assuming zero was needed, as I was not considering zero as a "loss". Thanks for the help.
