why is my footer not at the bottom html code example

Example 1: why is my footer not at the bottom html

#footer {
   position:fixed;
   left:0px;
   bottom:0px;
   height:30px;
   width:100%;
   background:#999;
}

//name footer id="footer"

Example 2: how to fix the footer at the bottom of the page

#footer {
   position:fixed;
   left:0px;
   bottom:0px;
   z-index:1;
   width:100%;
}