MARS not working with sql native client

I have a C# application that export data to sql server using odbc connection. I got this error:

System.Data.Odbc.OdbcException (0x80131937): 
ERROR [HY000] [Microsoft][SQL Native Client]
Connection is busy with results for another command.

I have tried MARS_Connection=yes in the connection string but it is not working.There is no problem with sql native client 10 but the problem comes with sql native client(sqlncli). I found a solution in stackoverflow but I don't know how to implement SQLSetConnectAttr and other functions to enable mars.