The problem that many models of the GBA Gameshark, Codejunkies adapter, and Action Replay have is the size of the catridge lip VS the GBA slot on the DS. Most of them will work if you aply enough pressure on them. Sometimes it seems like you've put the adapter in all the way, but the cheaply made plastic is just a hair to larg to allow a proper fit for the contacts. Some times the force you need to make a good contact is enough to push the internal hardware on a DS out of wack so to speak. If you think you will break your DS from to much force then dont do it, of course. Try using an exacto blade to trim the plastic down on both the outside of the adapters edge and the inside as well. On top of all this, the slot on the adapter (for the GBA game pack itself) may not have enough room and the lower lip of the DS may be putting pressure on the pack. That can also cause the problem you are getting. Since most of the cheat adapters game pack slots are pretty thin, there is not much plastic to be removed from them. You can always sand off the bottom area of the DS (where the back of the cheat adapter and the bottom of the DS meet) to help this, but that would be just plain mean to the DS. Outside of these procedures (which are the most common solutions I've seen for this problem) dont forget the basic things first. Make sure the contacts for both parts of the cheat adapter are clean. Find a working GBA to try the unit in and make sure it still works. If so then you are back to doing what I posted above. Yes, they do work and there should be no technical issues with most of these adapters. The only real problem is the plastic housing and some elbow grease needed to make them fit correctly. If you take your time, you can do these mods without making the plastic look bad. Dont use a dremel and grinding drum unless your pretty good with them and have a decent vise to hold the adapter in. You will just end up making the adapter body look like you drug it behind a car on a long road trip. Dont use heat as it can cause the very thin contacts on the PCB to come lose or weaken. Just use an exacto blade (or any easy to hold razor blade) or some rough grit sand papaer (say 80 to 100 grit) and take your time.