Line Graph with 3 Lines
 

I am graphing 3 items on a line graph. Dollar amount, Percentage and Pieces. The dollar amount is the primary axis, the percentage is the secondary axis.
The first two months are plotted correctly, but for the third month the Pieces are plotted lower even though the amount is higher than the previous month.
I.E. - Feb = 11,000 & Mar = 15,000, but March is plotted lower on the graph.
Help?