96 vw jetta windshield wiper transmission case

so my old transmission case link broke so i only had one wiper, so I just got a used transmission case when putting it last night and hooked everything back up my wipers wouldnt go up and down it was like i put them on backwards...did i miss somthing or is there a special way it needs to go on?? im not having any luck i need a step by step or something please help!!!!!