Secondly, That is dumb to give you a remote key from another ML. Who is your dealer in San Diego, The New Remote must be sych to you ML when you have it, the NEw key isn't program yet to your ML. I order an extra key for my ML and I tried to sych it as per manual se,,, it didn't work so I have to take it to MB San Diego to make it work. they inserted my Key to the ignition then they program it thru lap tap computer. It took about 10 minutes. Take it to the dealer and have them fix it. Your is still warranty, correct?
and Third its weird that the dealer have only one key when you purchase your new ML. it's really something wrong.