GBA multiplayer cables don't work. The adaptor is designed for standard GB-color/pocket/DMG compatible "8-bit" cables with crossed wires (one end's output is the other's input). The GBA multiplayer cable does not have crossed wires.
I'm sorry that's not made clear on the page, I'll add a help section that explains this.

Sync works without the clock line, so a cable with a broken clock wire would still work for sync but not for data transfer.

Hi, I have the same problem, I can not update nl2 to 2.8.2, I continue with 2.7.9.1.
I followed the steps mentioned here Oliver, I have communication with the pc and usb adapter, "sync mode OK" in crome, "right orientation" ok, "after the select / start process it just displays GAME BOY for an eternity" .. .
I have two cable links, one the original "AGB-005" and another non-original, with the two cables I can sync and play the two gmadvance (master-nl2 and slave-nlone, and work great). Sorry, but I think I need to explain each step in detail, because I can not do that update.

success. the chrome app is really smooth. apparently the first cable i tried, before digging up another, was no good. the sync test was helpful for that.

: ^ )

success?

much love! thank you.

Please do not use the exe, especially don't double-click it.

To check if the adaptor responds properly, select the MIDI mode tab and click on "sync". It should immediately say "sync mode OK" below the buttons. If you see just "...", something is wrong with the MIDI communication.

Using multiple instances of nlmidi (the exe plus the web version or the web version in multiple browser tabs) or frequent double-clicking the exe may confuse the MIDI driver and / or the adaptor. For a fresh start, unplug the adaptor, restart the computer and use only the web version.

When you get the MIDI mode OK message, the adaptor works. If the update still doesn't work:

- Make sure the cable is connected to the adaptor with the right orientation:

- Make sure it's an "8 bit", e.g.  GB color / pocket compatible cable. GBA multiplayer cables (those with the extra bulge that makes them fit only the GBA link port) don't work.

You also need to download the latest ROM as well as the relevant bat file from the download page. You should open the bat, not the exe. (But you need all 3 files!)

http://nanoloop.de/update/index.html

Otherwise, the obvious question, have you inserted the adapter right away around into the link cable connector?

Does it appear under "sound, video and game controllers" in Windows device manager? Are you able to use it for MIDI?

In the off-chance that your adapter is really old, you may not be able to use the current software. If this is the case, it will use a green circuit board. (I don't actually know how many of these are in circulation, but I thought I'd mention it.)

where are the usb midi pro user gangsters at ? running windows 7 over here. got the chrome version of the "software" recognizing my shit but everytime i go to update the software after the select/start process it just displays GAME BOY for an eternity. the official .exe opens and closes the command prompt instantaneously every single time. pulling my own hair and teeth at this point. any help would be overly appreciated.

word.