All Arguments Must Use the Same Data Type and Compatible Units

If you get this error, make sure all arguments in the Expression have the same Data Type.

Example: Add a Number to a Length?

SUM (1, 2m)

This is incorrect, because the two arguments use two different data types: 1 is a Number, 2m is a Length.

Yet n the SUM Function, all arguments must use identical data types. (You can see this by opening Expression Editor and hovering over the SUM item.)

Solution

Change the expression so that both arguments use an identical Data Type (here, Length in meters).

SUM (1m, 2m)

The resulting Property is also a Length. Make sure the Property’s Data Type is set to Length.