I'm trying to make custom error bars for my bar graph, but inspector won't let me enter anything into the series section. The sections are not grayed out and I can still use the drop down menu. It was working a few minutes ago, but now it has stopped and I can't get it to work again. I'm using Numbers '09
If there is a parameter field taht you can't type into, then chances are that you haven't activated the feature that requires that field. For instance, if you can't type into the custom negative error bar field, make sure that you have enabled negative error bars.