buddypress custom header

Hi guys
Okay….I have installed BP on http://prosurfer.surfpeople.com.au and created a child theme as per the codex provided It’s very much in the development stage but I’ve come to a wall I cant seem to get over.
In my child theme I created a style.css and the inherited the css
by adding the code provided. this work fine and I started to change the body background, still this was okay.
But the header isnt playing ball.
I have an image ftp’d and added the css code to my child theme style.css, still good.
When I preview the site the my custom header image is hidden as there seems to be another style sheet? overridng my chld theme style sheet.
I use firebug to check the code and I can find the problem style there and de-activate it from fire bug which allows my custom header image to be visible but I have no clue as to where this is!
Ignore the dimensions as they will be changed soon.
Thanks in advance
Lee