Pivot Chart generated from Creator subform column

Hi

How do I make a pivot chart auto-regenerate when the underlying data in the subform it is based on is updated? If I have a pivot chart that is created from a main form it auto-updates the chart when ever I add new data via the form but if my chart is based on a column in a subform I can only get an updated chart by manually clicking on "regenerate" option.

Thanks

EDIT: Actually the chart based on the subform data will update automatically(synchronize) if I submit the subform data by using the subform submit button. In other words if I just view and use the subform and not the parent form. If the data in the subform fields are submitted via the parent form, the subform view data is updated but the chart isnt updated. I have to manually click on regenerate. I hope that makes sense.

So it seems the parent form submit button is not calling the report regenerate function for reports based on the parents subform.