Cannot insert the value NULL into column 'Id', Entity framework

I have the following model:

Services.StradaDataReview2Model.UOSChangeLog:

[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }

public int Accident_nr { get; set; }

public int Refnr { get; set; }

public int Action { get; set; }

public string Old_data { get; set; }

public string New_data { get; set; }

public DateTime SearchedFromDate { get; set; }

public DateTime SearchedToDate { get; set; }

public DateTime Changed { get; set; }

public string Username { get; set; }

public string Comment { get; set; }

Contracts.DataContracts.UOSChangeLog

public class UOSChangeLog
{
    public int Id { get; set; }
    public int Accident_nr { get; set; }
    public int Refnr { get; set; }
    public int Action { get; set; }
    public string Old_data { get; set; }
    public string New_data { get; set; }
    public DateTime SearchedFromDate { get; set; }
    public DateTime SearchedToDate { get; set; }
    public DateTime Changed { get; set; }
    public string Username { get; set; }
    public string Comment { get; set; }
}

Here Is how I Insert:

internal static bool SaveUOSChangeLog(List<Contracts.DataContracts.UOSChangeLog> values, string user)
{
    try
    {
        using (var ctx = new StradaDataReviewContext2())
        {
            var newVal = Mapper.Map<List<Contracts.DataContracts.UOSChangeLog>, List<Services.StradaDataReview2Model.UOSChangeLog>>(values);
            foreach(var val in newVal)
            {
                val.Username = user;
                val.Changed = DateTime.Now;
                ctx.UOSChangeLog.Add(val);
            }

            ctx.SaveChanges();
            return true;
        }
    }
}

When I run the code, I get the following error:

InnerException = {"Cannot insert the value NULL into column 'Id', table 'StradaDataReview.dbo.UOSChangeLog'; column does not allow nulls. INSERT fails.\r\nThe statement has been terminated."}

How can I make an auto increment of the Id column?