My R4 Card will work on my friends but not in mine

First off, it doesn't sound like you have a manual: http://gbatemp.net/index.php?showtopic=41279
Second, you'll want to grab the proper firmware from http://r4ds.cn
Thirdly: Theres a good chance that the contacts in the problem DS are dirty, miht be a good time to do some NES-styled maintinence(blow the dust out) :P
Lastly, the r4 is the second worst cart out these days(it's got nothing but fakes and clones, as the real r4 essentially died off over a year ago, the worst being the TTDS for its random quality and fuse failures), you could do better and get something better, like an AceKard 2(it's a good cart, ~15$), or a CycloDS(though the cyclo is the most expensive cart out, but its features are said to be worth it; ~50-60$) The R4 has certain issues with certain games, often requiring patching or some degree of hacking.

The flash card version shoule match with the ds lite version .pls check it now.if still any problem,i Recommend you go to http://support.gameyeeeah.com/ , then click icon? Submit a Ticket ? to find your solution. There is plenty of online consultants can help you on video game accessories when your machine turn out any technical problem. The site is specializing in it for several years. The products not only contain r4 series but also quality accessories. MAKE A TRY. You will find this online store that can bring you safe fast convenient surprise. Good deal, you deserve do!