Can't remove Listbox items from listbox - silverlight

Question

I have a listbox in a Silverlight application.
The listbox:
<ListBox Grid.Row="1" Grid.ColumnSpan="2" Name="lbHazards" Margin="5"
MinHeight="75" ItemsSource="{Binding Path=HazListByTaskIDCollection}"
DisplayMemberPath="sHaz_Name"
IsEnabled="{Binding Path=IsEnabled}" />
In the view model I have
Private _HazListByTaskIDCollection As ObservableCollection(Of vw_HazList_By_TaskID)
Public Property HazListByTaskIDCollection() As ObservableCollection(Of vw_HazList_By_TaskID)
Get
Return _HazListByTaskIDCollection
End Get
Set(ByVal value As ObservableCollection(Of vw_HazList_By_TaskID))
_HazListByTaskIDCollection = value
'Used to notify CommonBase class that a property change has occured
RaisePropertyChanged("HazListByTaskIDCollection")
End Set
End Property
Then I have a sub in the viewmodel:
Public Sub FillHazList(ByVal iHazID As Integer, ByVal sHaz_Name As String)
Try
Dim yy = New vw_HazList_By_TaskID
yy.iHazID = iHazID
yy.sHaz_Name = sHaz_Name
HazListByTaskIDCollection.Add(yy)
Catch ex As Exception
DisplayError("Error Happened", ex)
End Try
End Sub
And that works perfectly when this Sub is called the item is added to the listbox.
But I also need to be able to remove the items from the listbox
So I thought it would be easy enough so I created another sub
Public Sub RemoveHazListItem(ByVal iHazID As Integer, ByVal sHaz_Name As String)
Try
Dim yyy = New vw_HazList_By_TaskID
yyy.iHazID = iHazID
yyy.sHaz_Name = sHaz_Name
HazListByTaskIDCollection.Remove(yyy)
HazListByTaskIDCollection.Clear()
Catch ex As Exception
DisplayError("Error Happened", ex)
End Try
End Sub
This runs with no errors but it does NOT remove the item from the listbox.
What am I doing wrong?

Answer 1

Your RemoveHazListItem method appears to be creating a new vw_HazList_By_TaskID object, putting a couple of values in it, and attempting to remove this newly-created object from your collection. It seems you're not getting the behaviour you are expecting because you're attempting to remove from a collection an item that was never added to it.
As far as I can see, there are two solutions to your problem:
Override Equals in your vw_HazList_By_TaskID class. Doing this should allow new objects to be considered equal to existing objects in the collection, and hence you should be able to remove objects from the collection by passing to Remove an object that is equal to the one you want to remove.
Look through the collection for a vw_HazList_By_TaskID object with matching iHazID and sHaz_Name properties, and remove that object from the collection instead.
Incidentally, the Remove method of the ObservableCollection(Of T) class returns a Boolean value indicating whether it was able to remove a value from the list. In the event of the item to remove not being found, it returns False as opposed to throwing an exception.

Answer 2

Try like this:
HazListByTaskIDCollection.RemoveAt(HazListByTaskIDCollection.IndexOf(yyy));