Convert string to datetime

I am trying to convert a date string from one format to another. However, I am getting this exception error

The string was not recognized as a valid DateTime.

My code looks like this:

string theDate = "28-Feb-13 4:00:00 PM";

DateTime tempDate = DateTime.ParseExact(theDate, "dd-MMM-yy hh:mm:ss tt", CultureInfo.InvariantCulture, DateTimeStyles.None);

convertedDate = tempDate.ToString("yyyy/MM/dd hh:mm:ss");

      

        
        
        
      

    

I seriously don't know what went wrong.