Have you tried selecting it manually and see if it can communicate with any modules.................?

 98 model year is pretty old and might still retain  a circular diagnostic connector under hood requiring the Benz 38 adapter. I think in Europe there is a 14 pin adapter too for some application, possibly Sprinter. Sometimes you need to call the dealer parts department with the VIN # and see what Nazi Enigma code and KW engine  Autel wants you choose is the correct multiple choice. Some times you just want to say F@ck This  and exit and go into generic OBD2

  Like I said you may have to call the Dealer parts department with the VIN and find out exactly which Farfignueggen code and KW output motor the Teutonic Turd has got under the  hood , then bust his balls 5 minutes later to ask about some other equipped option code? Best paint codes it has on the radiator support for future reference LMAO.