GBIC configuration on a 3550

I am trying to connect two buildings using fiber. We have in place fiber to copper converters currently.

We have GBIC 1000base SX installed in 3550 but no green light. On POST, green light comes, but goes out.

Confirmed no shut for interface. When I sho interface I see Gigabit Ethernet Interface 0/1 is down, line protocol is down (Not Connected).

I removed the fiber from the converter, pulled the copper and plugged in the fiber. This is how I know the fiber is working fine.

Any other configuration hints or troubleshooting steps for me?

thanks