Cannot load SD with RC2 or RC1

[polyfusion]

Have a DC which I piggybacked flashable BIOS, flashed the BIOS file, "sd_loader_with.bios" onto it. Had previously link83 BIOS, and it worked fine.

Built an SD adapter, and have a 1GB SD card, and tried putting the RC2 DS folder onto it, but initially got "can't find DS_CORE.bin", say it was called "1DS_CORE.bin", renamed it, and it halts at the "Executing..." message.

Tried again with the RC1 DS folder, same thing with the 1DS_CORE.bin file, but this time, the system goes through a repeating loop of "Detecting SD card, etc., etc., Executing...", then screen goes blank, and then repeats the messages, etc.

I then tried putting the DS folder from archive "DreamShell_4.0.0_Beta4_(From_SD_loader).7z", and it loads ok to the DS desktop.

RC1 and RC2 still don't load.

Can anyone tell me why this is happening, and reasons (hardware is unchanged throughout)? Any solution to get RC1 or RC 2 working?

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Forgot to say, I'm trying to load Dreamshell from the SD card, WITHOUT using CD in GD-ROM drive.