sorting - Sort a list of objects by parameters in c# -

i have list of users.

i'd sort list few parameters.

            case 0:                 //date (work) int   example: 0                 osu_ve.userlist.sort((e1, e2) => e1.index.compareto(e2.index));                 break;              case 1:                 //name    (work) string     example: vectis                 osu_ve.userlist.sort((e1, e2) => e1.udata.username.compareto(e2.udata.username));                 break;              case 2:                 //pp      (doesn't work)  string   example: 14688.76                 osu_ve.userlist.sort((e1, e2) => convert.todouble(e2.udata.pp_raw).compareto(convert.todouble(e1.udata.pp_raw)));                 break;             case 3:                 // best pp (doesn't work) string   example: 820.545                 osu_ve.userlist.sort((e1, e2) => convert.todouble(e2.ubestscore[0].pp).compareto(convert.todouble(e1.ubestscore[0].pp)));                 break;              case 4:                 //rank   (work)   string  example: 48484                 osu_ve.userlist.sort((e1, e2) => convert.todouble(e1.udata.pp_rank).compareto(convert.todouble(e2.udata.pp_rank)));                 break;              case 5:                 //country rank  (work)   string  example: 54                  osu_ve.userlist.sort((e1, e2) => convert.todouble(e1.udata.pp_country_rank).compareto(convert.todouble(e2.udata.pp_country_rank)));                 break;              case 6:                 //acc (doesn't work)   string    example: 98.5678623                 osu_ve.userlist.sort((e1, e2) => convert.todouble(e1.udata.accuracy.remove(5)).compareto(convert.todouble(e2.udata.accuracy.remove(5))));                 break; 

i error message: input string not in correct format.

few of them works. problem?

decimal mark needs dot , not comma.
https://msdn.microsoft.com/en-us/library/zh1hkw6k(v=vs.110).aspx