I'm not 100% sure but a standard cable may work, your other half is correct when he says it should have come with one.

theres a bit of info about what you have here :


If you cant get it working with a USB cable, make a request in the BST for an old supercard style DS card, these also work on the GBA and Im sure theres plenty of people wanting to get rid now they have upgraded to R4 style cards (for the DS only)