Airbag lamp does not run out....

Hello, everybody!
I wanted to use my error memory on Saturday. Let airbag read out.
As I wrote a few weeks ago, my airbag lamp only goes after approx. 2 min. ==References== So to the VAG workshop. Only what did they have to find out?
The pin for the airbag (I think plug No. 3) missing !!! Even the master was perplexed. How can I have my airbag checked now ?? Has something changed in the different model years? Who knows advice?
I have an exclusive 4.2 year 11/91.

Thank you in advance and greeting, Matthias ZW