Com object is not binding using microsoft.office.interop.excel in C#

 i am binding an excel coloumn using c#.I need to bind the date coloumn in my excel.There is a constant year alredy in my excel cell like 1980. I need to append random "mm/dd "to it.I am using  Microsoft.Office.Interop.Excel here. i have tried the following code but it lost the constant year value.how can i fix? My cell format in excel is General.I tried diffrent formath though.



i am getting like  8/6/System.__ComObject instead of 08/06/1

for (int i = 2; i <= totalRows; i++)
            {
               
                xlWorksheet.Cells[i, 8] = GenerateRandomDates()+ xlWorksheet.Cells[i, 8] ; //not working expected 02/03/1980
              

            }



  public string GenerateRandomDates()
        {
            DateTime start = new DateTime(1995, 1, 1);
            int range = (DateTime.Today - start).Days;
            DateTime dt = start.AddDays(gen.Next(range));
            int month = dt.Month;
            int day = dt.Day;
            string formatted = string.Format("{0}/{1}/", month, day);
            return formatted;

        }