Silverlight 2 ArgumentException - silverlight

Question

I have a silverlight 2 app that has an ObservableCollection of a class from a separate assem/lib. When I set my ListBox.ItemsSource on that collection, and run it, I get the error code:
4004 "System.ArgumentException: Value does not fall within the expected range."
Here is part of the code:
public partial class Page : UserControl
{
ObservableCollection<Some.Lib.Owner> ooc;
public Page()
{
ooc = new ObservableCollection<Some.Lib.Owner>();
Some.Lib.Owner o1 = new Some.Lib.Owner() { FirstName = "test1" };
Some.Lib.Owner o2 = new Some.Lib.Owner() { FirstName = "test2" };
Some.Lib.Owner o3 = new Some.Lib.Owner() { FirstName = "test3" };
ooc.Add(o1);
ooc.Add(o2);
ooc.Add(o3);
InitializeComponent();
lb1.ItemsSource = ooc;
}
}
But when I create the Owner class within this same project, everything works fine.
Is there some security things going on behind the scenes? Also, I'm using the generate a html page option and not the aspx option, when I created this Silverlight 2 app.

Answer 1

Are you trying to use a standard class library or a "Silverlight Class Library"?
Because Silverlight 2 uses a subset of the CLR it cannot access standard class libraries that were compiled using the full CLR. To use an external assembly you must create it as a "Silverlight Class Library". This will create a project that only includes the namespaces available to Silverlight and will allow you to reference the assembly within your Silverlight project.
Check out the MSDN article ".NET Framework Class Library for Silverlight" for more info.

Answer 2

It may be because you're not handling a failure in SubmittedChanges(). See http://www.scottleckie.com/2010/04/code-4004-unhandled-error-in-silverlight-application/ for more info

Answer 3

Everything is in one project now.
Yes, but not like you just did it, instead, share, link to the file(s).
For this an old jedi mind trick of Silverlight when there is a need to share common entity code between the app and the service. This is done when the library could not be brought in due to the differences in .Net/CLR.
The trick is to include the file as a link into the other project. Here is how
In the target (Silverlight project) folder which needs the code file, right click and select Add then Existing Item... or shift alt A.
Browse to the location of the origins file(s) found and select the/those file(s).
Once the item(s) have been selected, then on the Add button select the drop down arrow.
Select Add as link to add the file(s) as a link into the folder.
Once done, there is only one copy, but built in two different places.
That will give access to the file as if the file was actually within the project's folder, but the file physically resides elsewhere...and avoids CLR issues.