Hi @bob
This issue was already discussed in a different topic.
@seewhy reply is correct.
You are performing a calculation in row 25 (${total_cal}).
The calculation in row 26 is redundant per se, and should be removed (you cannot enter an integer and perform the calculation at the same time).
Depending on what you want to achieve, you would need to edit row 26.
a) if for some reason you want to validate the total entered by the user, you need to enter .=${total_calc} in the constraint field
b) if you want to display to the user the total (i.e. automatic calculation) you would write ${total_calc} in the label field.
I hope this helps!
Best,
Andrea