"I have the ais transponders nmea tx wires connected to the nmea in on the converter"
In theory that is right, but in practice whenever an rx/tx pair isn't working, the best thing to do is reverse the wires and see if that fixes it. Apparently there are A LOT of things out there labelled "TX" meaning "Connect your TX wire here, this is my RX port" when they all should be labelled "this is MY TX OUTPUT" and vice versa.
Hiring a copywriter, an illustrator, a translator, a proofreader, an engineer
...Why hire five skilled pople to write a manual when your cousin can knock it off in the basement after school
Unless whatever you have connected to the NMEA input, isn't actually putting out NMEA data strings, or is putting out the wrong version. I've seen a GPS happily chattering away in something like version x.3 and being ignored, while setting it to version x.0 or x.1 all of a sudden makes things happy. Doublechecking all the menu options sometimes is all it takes. But first take some Bonine or Marezine, they have sedative value.<G>