Sync problems answering phone call

[jcortright]

I just got a used 2008 Ford Focus with Sync. My blue tooth phone paired with the system and I can make calls out with voice activation or dialing from the num pad on the dash, but I'm having great difficulty answering a call. The manual says to press the button with the phone icon. My steeringwheel button has 'OK" on the right side and a phone pic on the other left side of the button. When the phone rings, I hear it over the speaker system, see the caller ID number displayed, and then press the "OK" with differing results. Somtimes, it doesn't answer the call at all. Sometimes, it answers, I hear the caller for about two seconds, and then I see "Called Ended" on the screen actually while the caller is still speaking, then it's cuts off. I've tried holding down the "OK for several seconds, also just tapping it and letting go. I realize there's a bit of delay in response time as when I go to end the call, I press the steering wheel phone button to the left and hold it down as the manual instructs, and it still takes about 5 seconds to disconnect the call. Am I missing a step in trying to answer a call, or is there something broken in my phone button?