I'm not sure why the last statement doesn't work b/c that is what I would do. But an easier way to handle this is to go to the menu options File > Options > Reporting tab. Click the NULL checkboxes so that nulls are converted to zero (or an empty string).
I cover how to handle nulls in your formulas in Chapter 6 of my Encyclopedia book. You can find out more about my books at
Amazon.com or reading the
Crystal Reports eBooks online.