Legend Names in Line Chart

Hi All,
I am a new learner and user of Crystal reports. I have one query. I have made a line chart. I have made it thru chart expert, in that the names of the legends were automatically created by the software and I have no ways to change it.
eg. My table structure is

Week Date
Plan Number
Actual Number
Forecast Number

On my X-Axis the vales of weeks are shown and on Y Axis -- forecast, Actual and Plan values are shown. SO when I create a grapf, the legend names are automatically given by the software as.... sum of plan......
sum of forecast
sum of Actual

I want to change it to Just Plan, Actual, Forecast. How to go about it?

Please help me as I have to submit my work to client in few days.


Thanx & Regards
Varsha