Simple MSChart question

[izo_mezzo]

Hello, I am working on a simple program. But I am having trouble with MSChart and my DataGrid which is filled using an ArrayList. The problem is I cannot assign a DataGrid to the Chartdata of the chart. I think it may be my ArrayList but I'm not entirely sure how to fix it. The problem I get is a Bad Function Argument on the line

Chart1.ChartData = ReadingDataGrid

I'm not entirely sure why. Thanks in advance. Bye

Public Class Form1
    Inherits System.Windows.Forms.Form
 
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
 
  Chart()
    End Sub
 
    Sub Chart()
 
 
        Dim patient1 As New Patient
        patient1.ReadingProperty = 1
        patient1.ReadingValueProperty = 50
        myCollection.add(patient1)
        patient1.ReadingProperty = 2
        patient1.ReadingValueProperty = 60
        myCollection.add(patient1)
        patient1.ReadingProperty = 3
        patient1.ReadingValueProperty = 80
        myCollection.add(patient1)
 
        ReadingDataGrid.SetDataBinding(myCollection.myArray, "")
        Chart1.ChartData = ReadingDataGrid
       
 
        'Add a title and legend.
        With Me.Chart1
            .Title.Text = "Sales"
            .Legend.Location.LocationType = _
               MSChart20Lib.VtChLocationType.VtChLocationTypeBottom
            .Legend.Location.Visible = True
        End With
 
        'Add titles to the axes.
        With Me.Chart1.Plot
            .Axis(MSChart20Lib.VtChAxisId.VtChAxisIdX).AxisTitle.Text = "Year"
            .Axis(MSChart20Lib.VtChAxisId.VtChAxisIdY).AxisTitle.Text = "Millions of $"
        End With
 
        'Set custom colors for the bars.
        With Me.Chart1.Plot
            'Yellow for Company A
            ' -1 selects all the datapoints.
            .SeriesCollection(1).DataPoints(-1).Brush.FillColor.Set(250, 250, 0)
            'Purple for Company B
            '.SeriesCollection(2).DataPoints(-1).Brush.FillColor.Set(200, 50, 200)
        End With
 
    End Sub
 
End Class

Public Class CollectionList
 
    Public myArray As ArrayList
 
 
    Public Sub New()
        myArray = New ArrayList
    End Sub
    Public Sub Add(ByRef T As Patient)
        myArray.Add(T)
    End Sub
    Public Sub Remove(ByRef T As Patient)
        myArray.Remove(T)
    End Sub
    Public ReadOnly Property Count() As Integer
        Get
            Return myArray.Count
        End Get
    End Property
    Public Function GetTrack(ByVal index As Integer) As Patient
        Return myArray.Item(index)
    End Function
 
End Class

Public Class Patient
 
    Private Reading As Integer
    Private ReadingValue As Integer
 
    Public Property ReadingProperty() As Integer
        Get
            Return Reading
        End Get
        Set(ByVal Value As Integer)
            Reading = Value
        End Set
    End Property
    Public Property ReadingValueProperty() As Integer
        Get
            Return ReadingValue
        End Get
        Set(ByVal Value As Integer)
            ReadingValue = Value
        End Set
    End Property
End Class