Header image vanishes on classified listing pages


If you have a look here: http://www.123onlineltd.com/social/classifieds/

You will see the header image is fine (it is one I have uploaded and I am using your BP Colours theme and child themes). The header works fine throughout the site but as soon as you go to a classified listing it reverts back to the themes default header, see: http://www.123onlineltd.com/social/classified/helios-5s-body/

Please advise how I fix this so the uploaded header appears on this page.

Thanks in advance