[SOLVED] CSS - Browser won't load background image

[Kinetic_lord]

I am building a site and, i edited a few pictures to use as menu's, buttons, etc... The problem is, i have placed the background of the main header using: background-image: url('menu/bar_menu'); When i see the preview in Quanta plus, the background appears, but in Firefox, i can only see the buttons and a white background. This is the CSS:

#header {
top: 0px;
left: 0px;
width: 800px;
background-image: url('menu/bar_menu.png');
}

#left_menu {
top: 250px;
left: 0px;
width: 250px;
background-image: url('menu/bar_left.png');
}

#content {
top: 250px;
left: 250px;
}
So what is the problem? The Web Developers toolbar in Firefox shows no CSS errors.

[Kinetic_lord]

Found the problem! Thanks for the help! :)

[TreeFinger]

so what was the problem?

[Kinetic_lord]

I wrote: <link type="text/css" href="style.css" />

i should've wrote: <link type="text/css" rel="stylesheet" href="style.css">