Window services cant trigger exe

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service

I make one window service in c#
to run exe on particular time., but it could open that exe,
Below is code

private static string   checkdatentime()
       {
           currentdate = DateTime.Now;
           string value = "1";
           for (int i = 0; i < xml_date.Count; i++)
           {
               value = "2";
               if (currentdate.Date < xml_date[i].Date)
               {
                   value = "3";
                   break;
                   // go out side for loop;

               }
               else if (currentdate.Date > xml_date[i].Date)
               {
                   value = "4";
                   //Do nothing means loops continues

               }
               else
               {
                   value = "5";
                   //if both date are same

                   if (currentdate.Date == xml_date[i].Date)
                   {
                       value = "99";
                       currentTime = currentdate.ToString("hh:mm");
                       TriggerTime = newItem.TriggerTime.ToString("hh:mm");

                       if (currentTime == TriggerTime)
                          {
                              value = "6";
                           //Run EXE
                              System.Diagnostics.Process.Start("E:\\SqlBackup_Programs\\console-backup\\Backup_Console_App 22July Latest\\Backup_Console_App\\Backup_Console_App\\bin\\Debug\\Backup_Console_App");
                           return value;
                        }

                   }


               }


           }

           return value;
       }

NOTE: here I return value because to verify is my code runs correct or not and write VALUE on text file, so on same time I am getting VALUE=6, means there is no problem in code,
But still service cant open this exe,
by same code i made console application and its runs perfectly, so why not services??

Is this any problem with command,

System.Diagnostics.Process.Start();

kindly help me!!