title: EF 4.1 Code First: "non-null value of type 'DateTime'" Issue
body: <p>After initial dev and testing I have now pointed my MVC3 application at an existing database which contains live data.</p>
  
  <p>However I am getting this error related to the field called Date1 of type "datetime".</p>
  
  <pre><code>The 'Date1' property on 'StaffAttachment' could not be set to a 'null' value. You must set this property to a non-null value of type 'DateTime'. 
  </code></pre>
  
  <p>Is this telling me that all rows in the date must have a date and not be null? What do I do if I dont want to set a date on specific row?</p>
  
  <p>Can anyone offer advice on resolving this issue?</p>
  
  <p>Thanks Paul</p>
  
  <p>EDIT 1 (Posting Model)</p>
  
  <pre><code>public class StaffAttachment
  {
      [Key]
      public int AttachmentID { get; set; }
  
      public int? StaffID { get; set; }
  
      public int? TypeID { get; set; }
  
      [Required]
      [DisplayName("Proof of ID")]
      public int? AttachmentTypeID { get; set; }
  
      [Required]
      [DisplayName("ID Reference")]
      public string Reference1 { get; set; }
  
      public string Reference2 { get; set; }
  
      public string DateType { get; set; }
  
      [DisplayName("Expiry Date")]
      public DateTime Date1 { get; set; }
  
      [Required]
      public DateTime Date2 { get; set; }
  
      public DateTime Date3 { get; set; }
  
      public DateTime Date4 { get; set; }
  
      public string AttachmentPath { get; set; }
  
      public int? ValidatedUserID { get; set; }
  
      public DateTime ValidatedDate { get; set; }
  
      public int? CreatedUserID { get; set; }
  
      public DateTime CreatedDate { get; set; }
  
      public int? EditedUserID { get; set; }
  
      public DateTime EditedDate { get; set; }
  
      public TimeSpan TimeStamp { get; set; }
  
      public string FileName { get; set; }
  
      public byte[] FileImage { get; set; }
  
      public int AttachmentSection { get; set; }
  }
  </code></pre>