Using linqdatasource.Selecting event with session object

I've got a page with a gridview that should display many 'Warranty's via a linq query, or if there is a particular 'Warranty' in my session variable then i want to only show that. The way i'd hoped to achieve this is with the following:

Code:

---

protected void ldsWarrantySearch_Selecting(object sender, LinqDataSourceSelectEventArgs e)
    {
        if (Session["Warranty"] != null)
        {
            List<Warranty> W = new List<Warranty>();
            W.Add(Session["Warranty"] as Warranty);
            e.Result = W;
        }
        else
        {
            var Records = from W in DC.Warranties
                          where (W.Postcode == txtWarrantyPostCode.Text || string.IsNullOrEmpty(txtWarrantyPostCode.Text)) &&
                                (W.PolicyId.Value.ToString() == txtWarrantyPolicyId.Text || W.MainProductWarrantyId.Value.ToString() == txtWarrantyPolicyId.Text || string.IsNullOrEmpty(txtWarrantyPolicyId.Text)) &&
                                (W.CustomerName.Contains(txtWarrantyName.Text) || string.IsNullOrEmpty(txtWarrantyName.Text)) &&
                                (W.Address.Contains(txtWarrantyAddress.Text) || string.IsNullOrEmpty(txtWarrantyAddress.Text))
                          select W;

            e.Result = Records;
        }
    }

---

Unfortunately, if the session variable contains my warranty the gridview displays nothing, even though i've checked e.result and it does get assigned.
I've also tried assigning just the warranty instance (not in a list) and that doesn't work either.

Any suggestions welcome!
Cheers.