C#比較2日間の間隔は1ヶ月を超えてはいけません

 private bool CompareDate(string JobDateFrom, string JobDateTo, int n)
    {
        DateTime DTJobDateFrom = Convert.ToDateTime(JobDateFrom);
        DateTime DTJobDateTo = Convert.ToDateTime(JobDateTo);
        DTJobDateFrom = DTJobDateFrom.AddMonths(n);
        if (DTJobDateFrom < DTJobDateTo)
        {
            return true;
        }
        else
        {
            return false;
        }
    }