external style sheet issue

[Shadowing]

I'm having a problem where adding the CSS below on a external style sheet is being ignored on my page but if I add it in the head of the page it works. anyone have any ideas of things i can check that could be causing this. I'm using a PHP if statement to choose when it should be echo in. but like i said it works putting it in the head section

div.relative{position:relative;width:100%;}

So if the session is set it echo's in the div relative

if (isset($_SESSION['mycache'])) {     					   echo '<div class="mycache">';  					   echo $_SESSION['mycache'];					   echo '</div>';											   unset($_SESSION['mycache']); echo '<div class="relative">';}

[TheGallery]

Maybe you have a mistake in your link tag for the external CSS?