What setup have you got there.  Have you definitely got the right adapter for your headunit?   
  
For instance, I know the sextons direct web site says for the Pioneer to use 29-007 however the correct one is actually the 29-020.  I'm sure you have alll the right bits but just in case? 
  
  
  
fitting a sony headunit.....believe i ve got all the right bits.i ll check again at the weekend