get Jquery to slidedown div more than once without refresh

get Jquery to slidedown div more than once without refresh

So in the Last part of an AJAX long poll I'm trying to get the output data
to be put in a div and slide down but it will only slide down once! It
will append the div everytime but no matter what i do it will only to the
animation once. I've been trying to get this to work for days now, please
help.
Here is the little piece of code that handles the slidedown.
if (var_IDcheck < verify['id']) {
var_IDcheck = verify['id'];
for (var i=0;i<var_IDcheck;i++){
$('#datacheck').prepend(verify[i]).slideDown();
}
}