PRISM navigation with combobox

[Ubuntu]

Dear All,

I have a silly issue, which I can't tell why it is happening.

I am using PRISM 4 with regions and navigation. I created a master region that has a data service shared through region context to all details views, and it opens(navigate to) the views that show the data in RadComboBoxs and normal textboxs.

ISSUE:
When the master opens the detail's view to display data ... everything is correct, combo are working fine ... ONLY if I change any value of one of the combox in any view and try to open a new view the combos don't show any data at all. but the recently opened views are still working okay, it only happens to the newly opened views after changing the value of any combo. also If I submit the changes before opening a new view everything is acting as expected.

I am binding the combo as follows:

<telerik:RadComboBox x:Name="cbxNatinalityID" IsEditable="True" IsReadOnly="True" Margin="0,0,0,5" Grid.Row="6" Grid.Column="1" Grid.ColumnSpan="3"
ItemsSource="{Binding Nationality,Mode=TwoWay,NotifyOnValidationError=True,ValidatesOnExceptions=True}"
SelectedValue="{Binding Path=CurrentTaxpayer.NatinalityID, Mode=TwoWay}"
SelectedValuePath="ID"
DisplayMemberPath="NatinalityAr"/>

The ItemSource is bounded to QDSCV which is loaded when the OnNavigatedTo is called on the details view as follows:

public void OnNavigatedTo(NavigationContext navigationContext)
{
    DataService = RegionManager.Regions[RegionNames.TaxpayerDetailsRegion].Context as IAvtDataService;
    Nationality = DataService.GetNationality();
    Nationality.Load();
}

What could be the issue here ... !!

Appreciate any help !!

[Ubuntu]

Dear All,

    I have found the real cause of the issue, it is the QDSCV, I believe I should move the question to that forums.

    Best