Changing graph info in Crystal XI at runtime

Hi

Im producing a report from my VB6 app which takes data from an access database.

The report has a bar chart which i need to change. At runtime i need to graph to eiher add or take away data depending on the number of hours need.

For example if i need 8 hours then the X axis should takedata from 8 specified fields, likewisefor th Y axis, the same should apply should i need 12 hours etc etc

Can this be done through VB or must it be done using crystal??

Thanks
Nathan