speed sensitive radio

Hey everyone,

I know I have this on my 2002 Ranger XLT but for some reason I can't get it to work. My buddies F150 works great and we set mine up the same way. I have the ford in dash 6 cd changer model. When the radio is on you push and hold the off button until the speed control appears. I set it and still doesn't work. Any ideas?

Thanks