Drawing Custom lines in a chart

[Devaki]

Hi,

I have a line chart inserted in a report. Y-axis ranges from +600 to -600.
I want to draw lines at +250 and -250 and show that all points that exists between these two ranges are valid ones and those gone out are invalid ones.
I don't want to give this in a formula but like to plot all the values first and then draw two range lines and show.
I tried using custom lines . But it allows me to draw at only one point either at +250 or -250 but i want to draw it both places.
How to do this? Please Help


Thanks
Devaki