Can anyone see why two results in the attached sheet are wrong?

I have a spreadsheet that calculates the number of days since the start date for a number of dates entered in a column. It seems to work for most dates but in two rows I get a a negative number.
Wrong result.ods

The results are not wrong, but your data is. Cell A31 contains 0018-03-31 instead of 2018-03-31 and cell A39 contains 0018-06-29 instead of 2018-06-29.

Thank you. I made the mistake of thinking the edit field showed me the value. Double clicking on the cell showed me the true value in the field. I have changed it and it is all fine now.

Please add a comment, don’t user an answer for that. And if the answer solves your question please tic the V