C# – SL3+RIA Services: what assembly is required to use InvokeOperation

My apologies for not posting the solution i found. Bosses threw more work at me than i could handle. :) Please note my solution may not be the best but since my knowledge in SL and RIA services are so new, i guess it may be excused. Initially i wanted to pass back rather complicated arrays from the code provided by our client, but effort and time restraints allowed me to only get it right to convert and return a List. Hope this helps in some way.

Client Side : Silverlight Code in the MainPage.xaml.cs i have a call to retrieve a list of data from the server side, to display in a dropDown list.

// Function called on load of the SL interface
// 'slayer' is an object of the Domain Service Class server-side
// 'this.gidSessionNumber' is just a number used in the demo to represent a session
public void loadPaymentTypeComboBox()
{
    InvokeOperation<IEnumerable<string>> comboList = sLayer.getPaymentTypeCombo(this.gidSessionNumber);
    comboList.Completed += new EventHandler(popPaymentCombo_complete);
}//function loadAllComboBoxes

// Event handler assigned
public void popPaymentCombo_complete(object sender, EventArgs e)
{
    InvokeOperation<IEnumerable<string>> obj = (InvokeOperation<IEnumerable<string>>)sender;
    string[] list = obj.Value.ToArray();

    // 'paymentTypeDropdown' is the name of the specific comboBox in the xaml file
    paymentTypeDropdown.IsEnabled = true;

    // Assign the returned arrayList as itemSource to the comboBox
    paymentTypeDropdown.ItemsSource = list;
}

In the Domain Service Class i have the associated function:

    [ServiceOperation]
    public List<string> getPaymentTypeCombo(string gidNumber)
    {
        // Build objects from libraries provided by our client
        SDT.Life.LifeCO.clsSystemCreator.CreateSysObjects(gidNumber);
        this.lobjSys = SDT.Life.LifeCO.clsSystemCreator.GetSysObject(gidNumber);

        // Rtrieve the ArrayList from the client's code       
        clsTextList comboList= this.lobjSys.lstPaymentType_PaymentQueue;

        // Get the length of the returned list
        int cnt= (int)comboList.Count();

        // Create the List<string> which will be populated and returned
        List<string> theList= new List<string>();

        // Copy each element from the clsTextList to the List<string>
        for (int i = 0; i < cnt;i++)
        {
            string status= comboList.Item(i).Description;
            theList.Add(status);
        }

        // return the newly populated List<string>
        return theList;
    }//end function getPaymentTypeCombo

It would seem not: RIAServicesOverviewPreview.pdf for PDC09.