Misnest

dUTIL can assist in the location of certain types of logic errors, primarily those involving misnesting of logical constructs or missing symbols.

In this case, the problem is easily solved by the same parentheses that ought to be used to prevent misnesting of arithmetic operations.

Are there tags in places where they're not allowed? Have you tried to misnest tags anywhere ?

Improper use can cause misnesting, operator precedence problems, duplication of side effects, and other problems.