I want to add more property for every shape
So I tried to create a cusom class that inherited from Nshape
but I failed because the Nshape has no new construction and is created by factory
How could I implement this functionality

This is my class and still not saving and give this message "Failed to save to file. Exception was: There was an error generating the XML document."
so please if you have a sample or if you can help me where is the error
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Imports System.Drawing
Imports System.ComponentModel
Imports System.Drawing.Design
Imports System.Collections.Generic
Imports Nevron.UI
Imports Nevron.UI.WinForm.Controls
Imports System.Reflection
Imports Nevron.Chart.WinForm
Imports Nevron.Diagram
Imports Nevron.Diagram.Shapes
Imports Nevron.GraphicsCore
Imports System.Xml
Imports System.Xml.Schema
Imports System.Xml.Serialization
("CreateCustomPropertiesSchema")> _
Public Class CustomProperties
Implements IXmlSerializable, ICloneable

#Region "Constructions ..."
Public Sub New()

End Sub
Public Sub New(ByVal strShapeName As String, ByVal strType As String, ByVal iWeight As Integer, ByVal strPhysics As String, ByVal iShapeImage As Integer, ByVal strDesc As String)
_ShapeName = strShapeName
_ShapeType = strType
_Weight = iWeight
_Physics = strPhysics
_ShapeImage = iShapeImage
_Decription = strDesc
End Sub

Public Shared Function CreateCustomPropertiesSchema(ByVal schemaSet As XmlSchemaSet) As XmlQualifiedName
Dim schema As XmlSchema = New XmlSchema()

Return ""
End Function

#End Region

#Region " properties ..."

Dim _Shapeid As Integer = 0
Public Property Shapeid() As Integer
Get
Return _Shapeid
End Get
Set(ByVal value As Integer)
_Shapeid = value
End Set
End Property
Dim _ShapeName As String = ""
Public Property ShapeName() As String
Get
Return _ShapeName
End Get
Set(ByVal value As String)
_ShapeName = value
End Set
End Property


Dim _ShapeType As String = ""
Public Property ShapeType() As String
Get
Return _ShapeType
End Get
Set(ByVal value As String)
_ShapeType = value
End Set
End Property

Dim _Weight As Integer = 0
Public Property Weight() As Integer
Get
Return _Weight
End Get
Set(ByVal value As Integer)
_Weight = value
End Set
End Property

Dim _Physics As String = ""
Public Property Physics() As String
Get
Return _Physics
End Get
Set(ByVal value As String)
_Physics = value
End Set
End Property

Dim _ShapeImage As String = ""
Public Property ShapeImage() As String
Get
Return _ShapeImage
End Get
Set(ByVal value As String)
_ShapeImage = value
End Set
End Property
Dim _Decription As String = ""
Public Property Decription() As String
Get
Return _Decription
End Get
Set(ByVal value As String)
_Decription = value
End Set
End Property

Private _Tasks As Dictionary(Of Integer, Task)
_
Public Property Tasks() As Dictionary(Of Integer, Task)
Get
Return Me._Tasks
End Get
Set(ByVal value As Dictionary(Of Integer, Task))
_Tasks = value
End Set
End Property

#End Region
Public Overrides Function ToString() As String
Return _ShapeType
End Function
#Region "Implement .."
Public Function GetSchema() As System.Xml.Schema.XmlSchema Implements IXmlSerializable.GetSchema
Throw New System.NotImplementedException()
End Function

Public Sub WriteXml(ByVal writer As XmlWriter) Implements IXmlSerializable.WriteXml
writer.WriteStartElement("ShapeCustomProperties", "urn:devx-com")

writer.WriteAttributeString("ShapeName", _ShapeName)
writer.WriteAttributeString("ShapeType", _ShapeType)
writer.WriteAttributeString("Weight", _Weight)
writer.WriteAttributeString("Physics", _Physics)
writer.WriteAttributeString("ShapeImage", _ShapeImage)
writer.WriteAttributeString("Decription", _Decription)
writer.WriteEndElement()
End Sub

Public Sub ReadXml(ByVal reader As XmlReader) Implements IXmlSerializable.ReadXml
Dim type As XmlNodeType = reader.MoveToContent()
If ((type = XmlNodeType.Element) And (reader.LocalName = "ShapeCustomProperties")) Then
_ShapeName = reader("ShapeName")
_ShapeType = reader("ShapeType")
_Weight = reader("Weight")
_Physics = reader("Physics")
_ShapeImage = reader("ShapeImage")
_Decription = reader("Decription")
End If
End Sub
Public Function Clone() As Object Implements ICloneable.Clone
Dim des As New CustomProperties
'Dim src As CustomProperties = DirectCast(MemberwiseClone(), CustomProperties)
des._ShapeName = _ShapeName
des._ShapeType = _ShapeType
des._Weight = _Weight
des._Physics = _Physics
des._ShapeImage = _ShapeImage
des._Decription = _Decription
Return des

End Function
#End Region

End Class