Object reference not set to an instance of an object.

[Dave 10169531]

I am getting the message "Object reference not set to an instance of an object." I know I am not initializing the variable correctly but I cannot find an example that can show me how. I am using the class ChargeBatch with ChargeItem to build data to be passed via a JSON string. I can deserialize in the class fine but when I try to populate the class ChargeItem to serialize it into a JSON string, I get the above error. Thank you in advance for any and all help. Below is my code.

Public Class ChargeBatch
    Public Property ChargeItems As List(Of ChargeItem)
    Public Property CommunityKey As Long
    Public Property EffectiveDate As String
End Class
'Charge Items
Public Class ChargeItem
    Public Property OwnerKey() As Long
    Public Property ChargeCodeKey() As Long
    Public Property Amount() As Double
End Class

Module APIARcharge

Sub Main(ByVal ParamArray args() As String)

        Dim iMyChrgItem As Integer = 0

        Dim CommID As String = Nothing
        Dim ARFile As String = Nothing

        If args.Length < 2 Then
            Throw New ApplicationException("Invalid or no parameters passed to this module.")
            End
        Else
            CommID = args(0)
            ARFile = args(1)
        End If

        If Not File.Exists(ARFile) Then
            Throw New ApplicationException(String.Format("File \[{0}\] does not exist.", ARFile))
            End
        End If

        ' Open input file and post
        Dim chgbtch As New ChargeBatch
        Using mystream As StreamReader = New StreamReader(ARFile)
            Dim recs As String
            While Not mystream.EndOfStream
                recs = mystream.ReadLine().TrimEnd
                chgbtch.ChargeItems(iMyChrgItem).OwnerKey = (CInt(Mid(recs, 11, 10)))
                chgbtch.ChargeItems(iMyChrgItem).ChargeCodeKey = CInt(Mid(recs, 21, 10))
                chgbtch.ChargeItems(iMyChrgItem).Amount = CDbl(Mid(recs, 47, 9))                    chgbtch.CommunityKey = CInt(Mid(recs, 1, 10))
                chgbtch.EffectiveDate = Format(Mid(recs, 41, 6), "mm/dd/YYYYT00:00:00")
                iMyChrgItem = iMyChrgItem + 1
            End While
        End Using

        Dim json As String = Newtonsoft.Json.JsonConvert.SerializeObject(chgbtch)

End Sub