how to convert string to custom date format

Question

string stringdate,sdate;

stringdate=dt.Rows[i]["Date"].ToString();

sdate = stringdate.Substring(0, 10);

//sdate='6/8/2014'

DateTime dtime=new DateTime();

dtime = DateTime.ParseExact(sdate, "M/d/yyyy", null);

MessageBox.Show(dtime.ToString());

In above code, there is an error although I convert string to correct date format. plz help me