I remember getting that era working. I concluded Mercedes was trying to be clever in making a protocol so complex nobody else could understand it (thus ensuring you had to use a dealer) - and then discovered they couldn't debug it.

each body model (nothing to do with year or style) was different so clearing dtc but nothing else is not a surprise.

i did get that working, but I last touched it in 2007 so I don't remember enough details to be helpful. good luck.