Does the fiber type match that of the media converters? When you order this type of Allied Telesys product, they ask you to specify not only the connector type (ST or SC), but the fiber media as well (MM or SM).

Allied Telesys uses part number logic that will make it obvious as to what you've got.

The point is that you could have boxes that are mis-matched for each other or--more likely--units designed for the type of fiber that you're not actually using!

What are the unit's part numbers and what color is the jacket on the fiber feed, orange or yellow? You might also need to flip the fiber pairs at one end only.

And I almost forgot! If I remember right, there are one or two pushbutton switches on the front of these units. Make sure both of them are in the non-test mode.

"Press play and record at the same time" -- Tim Alberstein