APEX

I'm trying to disable a button, but although the button changes appearance it is not disabled, I can still click it and it still works. So I tried to work around it by checking if the button is disabled or not before submitting, but then it does nothing. Please help!
This is my javascript function:

<script type="text/javascript" language="javascript">
function f_disableButtonSubmit(pThis, pRequest)
{
disItem = document.getElementById(pThis);
a = disItem.disabled;
if (a==false){
html_disableItem(pThis,true);
doSubmit(pRequest);
}
}

</script>