Series Titles (Legends) on pivot chart won't update after edit

[Ebkat]

Have a pivot chart with some series titles in the legend that I want to change. I click on the series, go to Analyze in the Pivot Chart tools, go into the Active Field and edit the name. One series works just fine, but the other one won't keep the edited name. It just reverts to the original name. These are Value fields, and instead of displaying "Sum of Widget Orders" , I just want it to read "Widget Orders". Any idea why it would work with one series but not another?