Why is EF trying to insert NULL in id-column?

Question

I am writing my project using Entity Framework 4.0 (Model first). At the beginning of the project, I faced with this problem: I am trying to insert the filled object in the

Answer 1

İf Model first try block

[Key]
 [DatabaseGenerated(DatabaseGeneratedOption.None)]
 public Int64 PolicyID { get; set; }