Firstly does it only read 4gb cards? I have a 2gb card, I also only use a DS lite. I put it in and it worked okay, despite my game file name being too long. I went to eat before editing the file name. I tried it again, and all it says now is that there is no DS Card inserted. So I ask do I need a 4gb card? Where is the most up to date firmware/kernal?
does your card have the gold/yellow star on the front saying v1.4 ? if so go to WWW.R4I-SDHC.com and download v1.22 for it, hope this helps