This is a bug in the first production of the English version of the game. The wall of the radio room is slanted (to make it look nice) and indy can't grab onto slanted walls. So, all jumps are futile. Also, some save games won't work with this bugged version of the game! You have to get a save game from the second English production or it will crash the game to windows, because the other versions of the game save differently!