Firstly i'd like to say that it my first time doing any to this and i completely new to it.
I have the slim loader IV and NEOKEY cart. i have tried using a 512 MB transflash card with and SD adaptor and a 64MB simpletech SD card. I have formated the cards to FAT16 and 32 and i have also exracted and re-built the nds roms with ds lazy. I have also tested my for version to see if its compatible, which it is i DO NOT get the yellow screens. I use the NEO power kit to put the NEO_MK2_3_Menu_V0.6-BETA_2 meus software on it. The NEO power kit does read and write to the NEOKEY but everytime i go onto the NEO power kit after burning the menu software to the menu never shows up on the cart, its like it was never burnt to it in the first place. I have also tried the Neo Max software and tried to format my cart with it but that doesnt work, i keep getting an error saying no cart or somthing. So can anyone help me??
*EDIT*
I also wanted to know am i surposed to be using clean roms or patched roms?, how do i know if i have a patched rom?, if i do can i un-patch it?
I'm not sure about the compatibility of your particular sd cards (if one it not compatible, you generally get a message saying that it failed to initialize the card, when trying to browse the contents using the menu).
Copy clean dumps onto the sd card via your sd card reader. You generally know it's a clean dump because it should be labeled as such (getting clean dumps is the easiest alternative). The menu patches the roms automatically, so that's why clean dumps are initially required. Don't worry about rebuilding/recompresing the roms, either.... the menu has a built-in trimming feature.
Get the latest version of Neo Power Kit (it sounds like you have it). Older versions will not recognize the neo-key. Next, flash the latest menu software onto your neo-key in nds mode (you double click that 'nds mode' icon on your desktop). After you have added the file and burned it, it should say that burning was successful. Don't worry if it doesn't show up in NPK (it lacks a proper gba header, so you won't see it listed, but it's definitely there).
Put your neo-key in the gba slot.... insert your sd card (loaded with clean dumps), and original ds game cartridge into your magic key 3 unit.... insert the magic key into the nds slot, and the menu should boot automatically.
BruceG