WPF Set SelectedValue for ComboBox on page reload - wpf

Question

I have a ComboBox that is created when the page is initialised
Dim CategoryCombo As New CustomControl.ComboCBx
With CategoryCombo
.Name = "MaintTypes_CatCombo"
End With
RegisterControl(MaintenanceTypes_Grid, CategoryCombo)
vToolBar.Items.Add(CategoryCombo)
vToolBar.Items.Add(TS_Separator)
and added to the toolbar
It is populated in the load event
Dim CatCombo As CustomControl.ComboCBx = MaintenanceTypes_Grid.FindName("MaintTypes_CatCombo")
With CatCombo
.IsNewRecord = False
.Width = 200
.ItemsSource = ReturnCategories.DefaultView
.SelectedValuePath = "ID"
.DisplayMemberPath = "Name"
.SelectedIndex = 0
End With
If the user navigates to another page and returns the selected value is returned to the selected index of 0. I can grab the last selected value before leaving the page but cannot find a way to set .SelectedValue when the page reloads
Data comes from
Private Function ReturnCategories() As DataTable
Try
CatDT = New DataTable
With CatDT.Columns
.Add("ID", GetType(Integer))
.Add("Name", GetType(String))
End With
With CatDT.Rows
.Add(0, "Select Category")
End With
Using vService As New Service1Client
strSQL = "SELECT Category_ID as 'ID', Category_Name as 'Name' FROM Maintenance_Categories "
strSQL += "WHERE Management_ID = " & Management_ID
strSQL += " ORDER BY Category_Name"
Dim DS As DataSet = vService.ReturnDataSetHAS(strSQL)
For Each Row As DataRow In DS.Tables(0).Rows
With CatDT.Rows
.Add(Row("ID"), ReturnText(Row("Name")))
End With
Next
End Using
Return CatDT
Catch ex As Exception
EmailError(ex)
Return Nothing
End Try
End Function
Any ideas?
Thanks

Answer 1

Found a workaround - return the index from the DataTable and set the .SelectedIndex of the ComboBox with that
In case someone has deleted the selected item prior to returning to the page check the row exists first
Dim vIndex As Integer = 0
If Not CurrentCategory = 0 Then
Dim vRow As DataRow = CatDT.Select("ID = '" & CurrentCategory & "'").FirstOrDefault()
If Not vRow Is Nothing Then
vIndex = CatDT.Rows.IndexOf(vRow)
End If
End If
With CatCombo
.IsNewRecord = False
.Width = 200
.ItemsSource = ReturnCategories.DefaultView
.SelectedValuePath = "ID"
.DisplayMemberPath = "Name"
.SelectedIndex = vIndex
End With