it's quite likely that your div is getting loaded after the javascript has run, which will render it meaningless. An iframe has an onload event which you could use to fire a function that would hide it once it exists.
or you could try using css just to hide it from the outset.
Code:
<style>
.ss-footer{display:none}
</style>
which reminds me, why if you are trying to hide it are you doing:
Code:
ele.style.display = "block";
?