PDF Report and new Field Total

Hello, we do lot of applications with Scriptcase method, and all the apps. works very well.
Now I must do a PDF report that, from a table. This table is join to another table that contains a lot of info.
The total is the result of ( ( time * quantity ) + setting ) / 60 .
Until I don’t use the filed “total” the app works well, when I apply the Total the system tell me : " Fatal error: Unsupported operand types in…" It indicates the row that contain just my formula.

All the filed are numeric .

Is there anyone who can tell me what it wants ??

Thanks in advance.

Are you calculating the field inside your SQL statement, or in the OnRecord event?

Maybe a code snippet might help