iPhone won't work well with Pioneer DEH-5900IB Car Stereo

Hi there, i have a pioneer DEH-P7750MP, with the CD-I200 cable to connect my ipod and it worked great, since it had a very good sound quality and charged the ipod at the same time.
Now i bought an iphone, and when i connect my iphone to the reciever with the CD-I200 it charges the ipod, but when i play any song or video, it sound through the iphone speakers, instead of sound in the reciever.
Anyone have an idea odf why is this happening to me or how can i solve it?
Thanks very much indeed for any help anyone can give me.
Richard Alves

Hi, I work in a car hifi shop in the UK, I've tried my iPhone with the huge majority of currents systems and can confirm that all Alpine units from last years and this years range are fully compatable. Almost all kenwood units from the last five years if used with the IP500 interface work perfectly. This years Clarions are fine. The only Pioneer unit which I have found that works properly is the AVH-P5900DVD.
Having spoken to Pioneer technical they say that it's not their fault, they say apple must have changed the firmware, they also didn't believe me when I pointed out that most of their competitors units perfomed fine. Based on this, I veru much doubt there will be a fix for people who own a current(or older) pioneer unit. You may be interested to note that the Dension iPod interfaces(gateway 100.300 and 500) work fine with iPhone.
I know Dension make interfaces that will connect iPods to aftermarket head units ie- Kenwood, Pioneer etc.. It would be a safe bet that if you used a dension interface with your Pioneer headunit via its IP-Bus(multichanger) input this would work fine but I haven't had the chance to test this theory, I will post again when I have.

I have the same stereo and cable in my cadillac, my iPhone 1.1.2 works perfectly not in airplane mode, syncs, charges, and displays properly on the radio. As well as my iPod Video 30Gb