Pie charts only visible when i click in chart

[oaio.jim]

I have a form with 4 pie charts. They are loaded from queries filtered by list boxes on the form. It was working great but now some of the charts don't show anything unless I click on the chart. If I select another person, in a list box, it updates the charts but maybe another chart will be blank...until I click on it. I didn't change any perimeters in the form. I did change values in the table that the chart's query pulls from. What would cause this to happen?

[June7]

Would have to evaluate data and form structure. If you want to provide db follow instructions at bottom of my post.