question

I am having below code with proper NULL Check, still i get the error

   using (conn = new SqlConnection(interconnecting))
             {
                 using (var query = new SqlCommand(customerInsert))
                 {
                     query.Connection = conn;

                     query.Parameters.Add("@Id", SqlDbType.NVarChar, 150);
                     query.Parameters.Add("@lastSignInDateTime", SqlDbType.DateTime);

                     conn.Open();
                       
                           
                         query.Parameters["@Id"].Value = user.NimbusUserCrmId.ToString();                            
                         if (user.LastSignInDateTime != null)
                         {
                             query.Parameters["@lastSignInDateTime"].Value = user.LastSignInDateTime;
                         }
                         else
                         {                                
                             query.Parameters["@lastSignInDateTime"].Value = DBNull.Value;
                         }
                         query.ExecuteNonQuery();                          
                        
                     conn.Close();
                 }
             }

Which throws the below error

SqlDateTime overflow. Must be between 1/1/1753 12:00:00 AM and 12/31/9999 11:59:59