Your brackets, operators, functions, or special variables were not selected from the Variables Panel.
Try selecting it again from the Variables Panel, or type curly brackets like these {{ }} so that it ends up with a background color:
{{ ( }}
{{ / }}
{{ + }}
{{ = }}
etc.
Wrong :
Correct 
:
I also suggest doing this Make Academy, as it covers selecting brackets, operators, functions, or special variables from the Variables Panel.
For more information, see:
- Error Handling Unit 2 - if condition always true - #2 by samliew
- How to make a basic SUM (x+x+x..) function in Make? Is it possible to use Numeric Agreggator? - #2 by samliew
- Formulas not evaluating in modules (Set Variable, Sheets) - Output is literal formula string - #2 by samliew
For more information, please refer to these courses in the Make Academy:
Transforming data using functions
- Introduction functions
- Transforming Data - Text functions
- Transforming Data - average ()
- Transforming Data - formatNumber
- Transforming date and time using functions
- Conditional functions
- String and array conversion functions part 1
- String and array conversion functions part 2
Using get () and map () functions
- The get() function
- The map() function
- The get() and map() functions
- The get(map()) use case
Hope this helps! Let me know if there are any further questions or issues.
— @samliew