cant make the body background appear in middle with no-repeat

cant make the body background appear in middle with no-repeat

i am trying to make a background for my page, i want it to appear in
middle but for some reason it shows on the left no matter what i do. any
suggestion?
body { font-family:Tahoma, Geneva, sans-serif; font-size:12px;
color:#696969; text-align:center; min-width:320px;
background:url(../images/background.jpg) center no-repeat;
position:relative; -webkit-text-size-adjust: none; }
i have created a seperate file and it showed in middle with the following
code:
<style>
body{
background:url('background.jpg') center no-repeat;
}
</style>
why doesnt it work on my original page?