Help with Progress Bar and tree view

[samo8076]

Hi guys,

Im using the standard Progress Bar in Silverlight 3. Im returning a dataset using LINQ and then populating a treeview by looping through the returned data.

What i want to do is show the progress of this through a progress bar.

The problem is progress bar only updates (or at least shows it) when the process had finished. Im not seeing the progress as i thought i would.

Here is my code

PlotXMLData = XDocument.Parse(e.Result)

TreeProgBar.Value = 0
Dim LettingCount = From i In PlotXMLData...<Letting> Select i.@LettingsID
TreeProgBar.Maximum = LettingCount.Count

'Dim Letting As Object
Dim n As Liquid.Node
For Each SiteNode As Liquid.Node In LettingsTree.Nodes
Dim intSiteID As Integer
intSiteID = SiteNode.ID

Dim Letting = From i In PlotXMLData...<Letting> Select i.@LettingsID, i.@PlotID, i.@SiteID Where SiteID.ToString = intSiteID.ToString

For c = 0 To Letting.Count - 1
n = New Liquid.Node
n.Title = Letting(c).PlotID
n.ID = Letting(c).LettingsID
SiteNode.Nodes.Add(n)

TreeProgBar.Value = TreeProgBar.Value + 1
TreeProgBar.UpdateLayout()

Next

Next

LettingsTree.UpdateLayout(

Any help would be great. Thanks