My R4 will not work

Hi i have purchased 2 R4 units and i can not get them to work on my older of my 2 DS consoles they both work on the newer model fine. Can anyone please tell me why this could be or how i can fix it.Cheers

Newer model as in Lite? What types of R4 are these?

The unit is R4 Revolution for DS (NDSL/NDS) and the console is a 2 year old DS

So is it a Lite DS or not? What happens when you try to get them loading?

Sorry my wife told me they are both DS lite units that i have not DS the newer one is 6 months old and the other is 2 years old.

did you install the firmware?
http://linfoxdomain.com/nintendo/ds/ is where I go to download it, just confirm the exact type of flashcart you have and you'll be allright.
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