I don't know C#. The online docs are rather opaque to me.

E.g. is it saying "do the following unless the field is zero"?

Try removing the (!0) text and seeing if it compiles. If so, there may be something wrong with the formatting of the instruction (e.g. maybe another set of parentheses are needed or something).

Otherwise, the standard debugging steps of "insert print statement" as needed may be the quickest way to figure out what it is doing.

HTH a little. Good luck.

Cheers,
Scott.