Does the other DS see the R4 card, or does it simply boot to the main DS menu? Is the DS in question a DS lite? You can try removing and reinserting the R4 into the DS a few times. I've had this occur in the past. It's almost as if it's not making a good connection with the contacts.
ITS AN DS NOT LITE R4 WORKS FINE WITH 3 OTHER DS WE HAVE BUT NOT THIS ONE AND ITS JUST THE MAIN MENU COMING UP
Can that DS play original games? Do you have any cards in slot 2? Make sure that slot 1 is clean (use canned air to blow it out).
