There is a logo and a banner those are 2 separate things.You uploaded your image as a logo not a banner.I assume you want your image to be a banner then you have to upload it as a banner.png remember it has to be 1240x220 px. I see it's a gif image so don't forget to change that in the css file.
• Project Durango
Want me to port a style to 3.2.x etc. contact me here or on twitter.