It's not a complete optical link.. only partial. That being said, you need to ensure that all end points are working. You need to step out the troubleshooting by putting what is commonly called a "loopback plug" at each link. This is an old term that basically means to loop back the signal on the current side of the link without having to worry about the other side you are trying to communicate. Once you have verified each side is working properly without having to talk to each other, try to integrate the two links. If it still does not work, then you know the problem is between the two optical link modules. If your settings match your devices settings, and you are still receiving a framing error, you may be experiencing noise on your serial line.
Not knowing anything about your configuration or type of hardware, it is hard to say exactly what parameters you have flipped or incorrect.