This does not sound like a battery issue.  Before you try for a return, try these things:

-Reformat the cartridge.  Reformat it a couple of times.  Do this to both the A side & the B side of the cartridge.  Then flash LSDj back onto it & try it.

-Use a different USB cable.  It's possible one of the prongs in the cable is not making a strong contact.  If that's the case, it can lose connection & quickly reconnect before you even notice.  If it does that while you're writing to the cartridge, then whatever you're writing WILL be corrupted & cause exactly the type of problems you're describing.  Also, to be safe, plug the cable in tight & DON'T TOUCH IT, especially while it's writing.  Place the cartridge down & do your flashing.

-Finally, check the Gameboy itself.  Please do keep in mind how old these things are.  The contacts where the cartridge plugs in may be dirty.  See if you can stick a Q-tip doused with isopropyl alcohol down into that contact area in the Gameboy.  Try to clean the contacts.  Isopropyl alcohol is used to clean electronics, so you don't have to worry about moisture damage or anything like that.  Try anyway you can to rub those contacts with alcohol.  Make sure you blow it dry before connecting & turning on.  Alcohol evaporates very fast.

Hope this helps.  Good luck.

ok, thats the latest batch, i doubt that is the issue.

did they flash anything to the cartridge for when it arrived?  test it in any way before shipping, i guess i mean,

check out their return policies, or get in touch with them directly and just ask about it.  everyone wants happy customers

The code is 1207

there is a code stamped on the back of the case, a date code.  usually 4 numbers,

what is the code? 

it tells the time of assembly, if it was from a while ago it *could* be your dealers stock just doesn't turn over regularly, then you could have gotten a dead battery.  thats possible, i don't know how quickly things move there of course,

I'd recommend looking into the carts yourself and deciding based on what you're looking for specifically, and how much you're willing to pay. nitro2k01 made a nifty post about the pros and cons of various usb cartridges a few posts down over here;
http://chipmusic.org/forums/topic/1277/ … o-request/

There's also Drag'n'Derp cartridges, which a lot of people are looking forward to, due to it's on board memory (no battery) but they're hard to come by at the moment and are fairly pricey. You can see more info from the creator here;
http://chipmusic.org/forums/topic/4170/ … boy-carts/

I personally use a BleepBloop because I'd heard the EMS carts are fairly unreliable (as a whole). I haven't had any issues with the cart or the drivers yet, after about a year and a half of use.

EDIT: Of course though, try to fix your EMS cart with what everyone else had mentioned first, best of luck on that end.

I opened my cartridge now...but nothing is taped there O.o

Oh and by the way, this is the site where i bought the cart:
http://dmgs-r-us.jimdo.com/shop/usb-cart-deluxe/

I'll try to replace the battery tommorow (need to buy one first) and if that doesn't help I will mail them a message.
If it's not possible to sent it back, could you guys recommend me a good cartridge? I have windows 7 64 bit...and I really have problems with installing drivers. Back then when i had xp it wasn't a problem because everytime i put in a new USB-device it gave me the option to install drivers from my hard drive, but now i don't get this message anymore...it just tells me that no drivers were found.

did you check the battery to see if it was loose (the cartridge one)?

also, can you explain the ROM configuration on your cartridge, as in what ROMs are in menu 1 and which ones are in menu 2?

edit -- also, can't believe i forgot this:

if the PCB shifts during transit that could really be the issue, they are taped in place but if they are jolted can still move, look up into the cartridge and you'll see how the circuit board and a lip on the cartridge case align.  the circuit board's edges should align EXACTLY with this.  if it shifts left or right enough your pins will touch and your cart will behave exactly like this.  out of like..  100 carts a couple will arrive like this, just not aligned correctly.  you just open the case, pry the circuit board up gently (its double-sided-taped down), and reapply it precisely aligned with that little lip on the cartridge case.

just something else to check

edit -- pry it up with something non-conduction, it is a bit of electronics after all.  a disposable plastic knife would work well, something along this line of thinking.  and, do it gently trying not to bend/warp the pcb since its adhered with tape.

I switched the batteries in both of my gameboys...didn't help. But i can't switch the batteries in my cartridge because i don't have those....need to buy them first

Again, check what I asked you. Are your batteries fresh? Any corrosion on the battery contacts? That is, in the Gameboy, not the cartridge's battery.

I don't know where you got it, but if you do have to return it when this is all said and done, you could ask the person you got it from to swap your front cartridge cases.

I tried to put Super Mario Land on the cart now...It worked, but when I put it into my gameboy and started it, nothing happens. The logo won't show up and i don't hear that typical *beep*-nintendo  noise...

I really hope my cart isn't broken <.< I almost waited 3 weeks for it to arrive and i already put a different sticker on it...so i don't think i could send it back again.

there could be many things that are inhibiting the sav:
-- dead battery
-- loose battery (just came out of its holder)
-- weak battery (if you just got the cart, shouldn't be the issue, also you generally get data corruption at this stage)
-- multiple ROMs with saving ability (they are overwriting each other)

confused about one thing you wrote though....  loading an 'empty' set should give you no pre-done data.  empty song should be empty.  i think i missed the 'problem' in that bit of info you wrote...  seems like loading and empty set, and getting emptiness, is just what was supposed to happen...

the NINTENDO logo can be a few things, a corrupted ROM, a bad connection between cart/console, or even the lack of a ROM (usually its not glitched, just missing some letters this way).  usually just reinserting it several times clears that up (the LSDJ manual even says to do this i believe).

the ROM disappearing itself is odd though. 

not sure if any of that rambling will even help!

edit -- yeah, and what nitro2k01 suggested too, change the batteries in your actual console too.  just to check and rule that out if nothing else...

Nitro's the boss, always take his word over mine.

If your battery contacts are dirty, you can clean them pretty well with a cotton swab and very careful application of some white vinegar—that will react with the corrosion and dissolve it on contact.

Oh, and another thing make sure you're not connecting the USB cable while the cartridge is in the Gameboy (whether or not the Gameboy is powered on.)

I actually believe the problem is that your batteries are going dry. The EMS cartridge draws more current than other cartridges, so even though your Gameboy might work fine with a game cartridge, the EMS cartridge might fail for this reason.
My advice would be to change to fresh batteries and also to look for corrosion on the battery contacts. If they're clean and the problem persists even with fresh batteries, you might look into the possibility of a faulty cartridge.