Retro Games Challenge ROM

I wonder if you guys could possibly help? I apologise in advance if I have this wrong, but I have searched and can't find any existing topics.I have a Nintendo DS Lite running a DSTT card, and a SANDISK 2GB memory card.I had a friend recommend Retro Games Challenge and thought I would try before I buy.However, I have an error with the ROM from here. Others I have work fine.The ROM does have a cross symbol by it (similar to in footie games when a player is injured) and the following message comes up :[ROM loading failed]
load rom errcode = 7Please reset system.If anyone could advise I would be very grateful.Is it worth trying to re download it?Thanks in advance.

this means it is not compatible with your flashcart, try updating the firmware (I assume it is an NDS rom, if not then things are a bit more complex).

Thank you for the reply.I thought I had the latest firmware but I may not do I guess....Will try and download the newest firmware and see.....

You sir are an absolute star!I am indebted to you!