How do I account for Missing Values in a Chart in RTF

I have a set of data showing project status.  There are 4 possible values for the status (Completed, Major Delay, Minor Delay, On Track).  In any given run of the report all, some or none of the status's might be applicable.  How can I do the following in a chart:

1) Color the status consistently.  (Generally you assign colors to a series, but it there isn't a value in a series then the order can shift)  I.e  Completed - Blue, Major Delay - Red, Minor Delay - Yellow, On-Track - Green

2) Show in the chart legend all of the values.

What makes this difficult is I am not guaranteed to have all of the status values in a particular report run.