S4 won't pair with my car stereo

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http://forums.androidcentral.com – A while ago I got a cde-133EBT alpine stereo. It worked fine with my iPhone 4, but it wont connect to my galaxy s4. I go to my settings, tap bluetooth, then tap the stereo reciever, but then I always get an "error" popup telling me that maybe my pin is wrong, but it never gives me a chance to enter it please help me soon or I might switch back to the iPhone. (HowTos)