Graphs

Column A shows the date of my entries. Column B and C shows data I am
entering from other sources. Column D I have addition formulas for columns B
and C.

When graphing the data I would like to graph through the end of the month.
For column B and C the graph line ends. For column D the graph lines flat
lines at 0 when data value is 0.

How do I graph (keeping the addition formulas) and not have the data flat
line?

Thanks