crm2011 - writing optionset values to the database using IOrganizationService

Create an enum in C#, with the same values as are in CRM2011:

public enum ApprovalStatus

{

    ReviewRequired = 657070000,

    Approved = 657070001,

    Rejected = 657070002

}

This is my method for doing the add:

   public void AddBillHeader(string org, ApprovalStatus approvalStatus, DateTime billingDate)

        {

            IOrganizationService svc = GetXrmService(org);

            Entity bh = new Entity("fcbt_billheader");

            bh["fcbt_billingdate"] = billingDate;

            bh["fcbt_approvalstatus"] = new OptionSetValue((int)approvalStatus);

            svc.Create(bh);

         }