I am trying to automatically calculate a date field. What I would like to do is take a permit date and add 180 days to calculate an expiration date. I added a date field for the final calculation. I open the field calculator and write the expression. The expression verifies correctly but when I calculate the field I get errors. I tried several different calculations to see if any of them would work. Below is an example of a calc I did to extract a date. Again, the expression verified correctly but then this error popped up when I calculated the field.