Ignore Series Values

Hi,

I'm working on creating a stacked bar chart report where the possibility exists for one of the "Series" values to be null.  To avoid getting the "Category series name is null" error, I played with the SQL query to give me a blank string value instead of null.  However, when creating my report, I then have a "blank" entry in my legend.  Is there a way to ignore values in the series argument if the value is empty?

Thanks!

Josiah