Its been my experience that data tables are notoriously "etched in stone". If I don't like what Excel presents, then I eliminate the data table and try to use textboxes with formula links to present the (portions) of data from the source. After creating a textbox, click into the box, and then type the source location as a formula in the formula bar above your chart; (eg., =Sheet1!A2). Its a workaround, and its time-consuming. But it may just enable you to achieve the effect you need.
Larry.