title: Sequence contains more than one element
body: <p>I'm having some issues with grabbing a list of type &quot;RhsTruck&quot; through Linq and getting them to display.</p>
  <p>RhsTruck just has properites Make, Model, Serial etc...
  RhsCustomer has properties CustomerName, CustomerAddress, etc...</p>
  <p>I keep getting the error &quot;Sequence contains more than one element&quot; (of type <code>InvalidOperationException</code>). Any ideas? Am I approaching this the wrong way?</p>
  <pre><code>public RhsCustomer GetCustomer(string customerNumber)
  {
      using (RhsEbsDataContext context = new RhsEbsDataContext() )
      {
          RhsCustomer rc = (from x in context.custmasts
                            where x.kcustnum == customerNumber
                            select new RhsCustomer()
                          {
                              CustomerName = x.custname,
                              CustomerAddress = x.custadd + &quot;, &quot; + x.custcity
                              CustomerPhone = x.custphone,
                              CustomerFax = x.custfax
                          }).SingleOrDefault();
          return rc;
      }
  }
  
  public List&lt;RhsTruck&gt; GetEquipmentOwned(RhsCustomer cust)
  {
      using (RhsEbsDataContext context = new RhsEbsDataContext())
      {
          var trucks = (from m in context.mkpops
                        join c in context.custmasts
                          on m.kcustnum equals c.kcustnum
                        where m.kcustnum == cust.CustomerNumber
                        select new RhsTruck
                      {
                          Make = m.kmfg,
                          Model = m.kmodel,
                          Serial = m.kserialnum,
                          EquipID = m.kserialno1,
                          IsRental = false
                      }).ToList();
          return trucks;
      }
  }
  
  protected void Page_Load(object sender, EventArgs e)
  {
      string testCustNum = Page.Request.QueryString[&quot;custnum&quot;].ToString();
      
      RhsCustomerRepository rcrep = new RhsCustomerRepository();
      RhsCustomer rc = rcrep.GetCustomer(testCustNum);
      List&lt;RhsTruck&gt; trucks = rcrep.GetEquipmentOwned(rc);
      
      // I want to display the List into a Gridview w/auto-generated columns
      GridViewTrucks.DataSource = trucks;
      GridViewTrucks.DataBind();   
  }
  </code></pre>