Visual Solutions Pack Chart Control

Does anyone out there use the Chart Control from the Visual Solutions
Pack (RAD Pack, Delphi 1)?  I can't understand how to add data to the
charts, although I can delete either all the data, or one point at a
time.  Deleting the first point is:

TKChart1.DeleteData:=0; {delete the point with the index 0}

so I thought I could use something similar to add a point, eg:

TKChart1.iDataArr[0]:=yvalue; {set the y value for point with index 0}
TKChart1.WriteData:=0; {write the point with index 0 to chart}

But this doesn't work...any suggestions would be very welcome.

Matt Spencer.