Air Bag Warning Light

Due to trouble with the Speedo & Tach performing properly on my 1997 Jetta I changed the instrument cluster with a used one. After installation the Air bag warning light stays on. If I put the old unit back the light will go off in the old unit. My thoughts are the system is working properly, but the new cluster is not synchronized with the system or the system needs to be reset because of the different cluster. Any help or experience regarding this issue would be greatly appreciated.

either
a: new cluster had a electrical problem in cluster
b: airbag module set code for no comm with cluster when you replaced it

either
a: new cluster had a electrical problem in cluster
b: airbag module set code for no comm with cluster when you replaced it
Thanks for the info:
A) Cluster electrical problem.
Is there testing with a multimeter to determine a problem? I know that terminals 1,2,12 & 13 relate to the Air Bag system on the terminal block.
B) No Communication code set by the system. Can a scan tool create communicaton with the cluster or clear the code?
Or is a Brand new cluster the real answer?

the likelyhood of a junk yard part having the same problem as the part on your car is, is very likely.... it is a vw..