I'm trying to play a mp3 cassette adapter in my '99 c280's factory stereo, but since there is a wire connected to the adapter, the face of the unit won't close all the way. Since it won't close all the way, the unit makes a really loud and onbnoxious beeping sound every 30 seconds or so. Has anyone figured out a way to get around this or are car cassette adpaters just not meant to work with the factory stereo? Any imput is useful. Thanks.