First of all, I want to initially thank anyone for responding to this situation. I've been researching this for a few days with no solution. Resorting to posting here and hoping someone will be able to help. Here it goes; I have 2 DS's here - Both are Mario bundle pack Red DS's.. I have an R4 III card that works fine in 1 DS, but will not load on the other DS. I initially thought the R4 card was a fake (this was before I had the other DS to check) Surprisingly, it booted up fine with no problems. So I figured the problem was with the actual DS itself. Whether it be a connection issue or internal firmware problem. I checked both firmwares by using the method the guy on youtube posted, to check the color of the screens. Both DS's displayed magenta screens. Which, as I understand, means both are version 4.0 firmwares. I've tried cleaning the DS Slot 1 with q-tips and rubbing alcohol and by using a can of air. Authentic games work fine, with absolutely NO problems, ONLY the R4 is giving me this problem. Again, I repeat; the other DS and R4 work fine together. I'm hoping someone can chime in and voice their suggestions as I try to find a solution to this nagging issue. Thanks in advance, and I appreciate you all taking the time to read this.