can't create new node using linq

I keep getting an error while trying to insert a new node by using Linq to umbraco.
www.grabout.com/Default.aspx

Here is the code I'm using:

 myContext = new Outpost11DataContext();
 ContactFormSubmitter aSub = new ContactFormSubmitter();
 aSub.EmailAddress = tbEmail.Text.Trim();
 aSub.FirstName = tbFirstName.Text.Trim();
 aSub.LastName = tbLastName.Text.Trim();
 aSub.ContactDate = DateTime.Now;
 aSub.PhoneNumber = tbPhoneNum.Text.Trim();
 aSub.Remarks = tbRemarks.Text.Trim();
 myContext.ContactFormSubmitters.InsertOnSubmit(aSub);
 myContext.SubmitChanges();

It seems that inserting new nodes isn't implemented yet. Is this correct?
If so, is there some other way to get this to work?