Power BI Values

Hello,

I have a database that contains date1 and date2 in which we update as we have the information. I made a formula to calculate the working days between these dates, but when a cell is empty a totally disbelieving value is returned, because I believe that the tool understands that it is a date X. How to change this? Because I want to make a comparison chart by month that returns values that are not real because it considers these values.