Problem adding ZedGraph curves with looping code

Hello all, I am new to vb.net & zedgraph so please be gentle...
I have the following very simplified code to add a number of zedgraph curves based on an array, but it appears to be clearing the curve on each 'for' loop?
If I comment out the zg1ppl.clear() it will generate a curve but then obviously it will accumulate all the PointPairs from all curves.
Any idea why this is happening?
(code below is muchly simplified for clarity)

Dim LabelArr() As String = {"FSinDay", "FSoutDay", "APinDay", "APoutDay"}
Dim zg1ppl As New PointPairList
'loop through label array
For c = 0 To UBound(labelArr)
     'generate a set of pointpairs in the pointpairlist
     For d = 0 To 10
           zg1ppl.Add(d,d+c+1)
     Next
     'add a curve based on the pointpairlist
     myCurve = myPane.AddCurve(LabelArr(c), zg1ppl,Color.Green, SymbolType.Square)
     myCurve.Symbol.Fill = New Fill(Color.White)
     'clear the pointpairlist ready for next curve
     zg1ppl.Clear()
Next

Tags: Visual Basic, ZedGraph