Yes, the dealer is the only place to get one, they'd need to order the little slide-in blade too. It's a different style now too, it's look like the keys do on the new ones, a little shorter, better for carrying in your pants pocket, and the panic alarm button is in a different place. They're kinda pricey though, I wanna say $125 or so. It may be the problem, but if not, at least you'd have a spare key. Dealer typically should be asking you for a photo ID and copy of the title (or just want to see the original title) to order it, MB has rules on ordering this stuff, so be prepared to actually go to the dealer to order it. For ease of ordering and use, I'd recommend buying what they call an "additional" key, not a replacement key.