Mark Bennett

Hello can u help... I have changed the original tape deck stereo from my 2003 Audi a4 with 2 separate aftermarket stereos and none of them have worked... I have connected everything that needs to b connected i.e the mains, speakers and aerial connectors yet no power to either of them... the original tape deck works fine and all fuses are fine...the 2 new stereos work fine in other cars... just wondering if there's anything I'm missing or whether there's a code specially from Audi that recognises aftermarket stereos??? I have tried to you tube it to see if anything different but most people are taking the double decks out whereas I've only taken the top single deck out so you tube was no help!!! The only other adapter that can b purchased separately is the aerial and I already have that and fitted it!!! Is there a code in the Audi manual that can help??? Any suggestions would b very appreciated thank U!!