Are these LED's and if so did you switch the direction 180 on the one that doesn't work? Pretty sure that bulb is # 14 on the board. I did an LED post where I logged each socket and identified positive 12v board socket sides here https://www.saabcentral.com/forums/showthread.php?t=721918. The post bobs and weaves as folks shared some great information.
If the bulb is good check the board socket with voltmeter to see if you are getting 12v on the positive side. If not inspect the board for a crack along the positive or negative trace and also check the pins, connectors and ribbons that attach the two circuit boards when you reassemble. Check the solder joints on the bottom side of the connector sockets as cold joints can crack when you are disconnecting and connecting a bunch of times.