Pivot chart with dual data set measued at different scales

I am using Access 2007 to create graphical representations of certain database data.  I have a Pivot chart that measures the cost and the quantity of a particular item on a month to month basis.  Both cost and quantity are measured as line graphs.  The problem is that the cost is always so high that the quantity get buried in the mud.  I have be able to create a new series for the quantity, with it's own seperate Y axis scale.  However the secont measuring axis is alway the same as the first.  How do I change the scale of the new group so that I can bring it's line up out of the mud.