Windows Forms application scan results in lots of 'dead code' issues, but code is executed

We scanned a windows forms application and get lots of 'dead code' issues, but we're sure the code is executed. I'm not sure how Fortify is supposed to know if code is dead or not, but since this presumed dead code does not seems to be inspected any further, it is not sufficient to mark the 'dead code' as not-an-issue.

How to fix this?