title: Simple LINQ insert record not working
body: <p>I have an .mdf file which I'm trying to add a record to, using linq in C#.
  My code is:</p>
  
  <pre><code>dbDataContext context = new dbDataContext();
  book b = new book();
  b.title = "Test Book";
  b.isbn = "123789";
  context.books.InsertOnSubmit(b);
  context.SubmitChanges();
  </code></pre>
  
  <p>When this code runs, the record is not inserted, and I get no error messages. If I use the database explorer to add a record with the <em>selfsame</em> data, it works.</p>
  
  <p>What's going on?</p>