SO I am changing the values in 2 different tables and the only table changing is the address table any one know why?

    protected void btnSubmit_Click(object sender, EventArgs e)
    {
        TestDataClassDataContext dc = new TestDataClassDataContext();
        var addr = (from a in dc.Addresses
                    where a.AddressID == Convert.ToInt32(ddlAddList.SelectedValue)
                    select a).FirstOrDefault();
        var caddr = (from ca in dc.CustomerAddresses
                     where addr.AddressID == ca.AddressID
                     select ca).FirstOrDefault();
        if (txtZip.Text != "" && txtAdd1.Text != "" && txtCity.Text != "")
        {
            addr.AddressLine1 = txtAdd1.Text;
            addr.AddressLine2 = txtAdd2.Text;
            addr.City = txtCity.Text;
            addr.PostalCode = txtZip.Text;
            addr.StateProvinceID = Convert.ToInt32(ddlState.SelectedValue);
            caddr.AddressTypeID = Convert.ToInt32(ddlAddrType.SelectedValue);
            dc.SubmitChanges();
            lblErrMsg.Visible = false;
            lblSuccess.Visible = true;
        }
        else
        {
            lblErrMsg.Text = "Invalid Input";
            lblErrMsg.Visible = true;
        }
    }