How to stop plotting empty cells in a dynamic area chart

Hi,
I have to update an area chart on a monthly basis(starting from say Apr-05 to Feb-06) . The X axis range along row is (B1:L1). The y axis values (y1,y2,y3) are linked to another workbook from which the y values are pulled out.the range being (B2:L2),(B3:L3)and (B4:L4) along row respectively. When i update the chart automatically, it dips at Mar-06 as there are no y values entered. Since this excel is an analysis of monthly forecast, there is no data for mar-06. How do I prevent the chart from dipping? I want it to stop there and not dip down to zero as there is no value available for mar-06.

P.S. I have taken a sample chart for explanation and entered y values manually as I am not authorized to share complany data. Kindly provide solution for this sample sheet data.