when you removed the old filter , did you get the old filter oring out of the hole the filter goes into.....if not, it is stopping you from getting in the new filter in properly...you will probly need a pick to get the old one out, they sometimes just can be pilled out with the filter or a finger ..but I have allways had to use a pick on mine......it looks like a dental probe....they are cheap ........once you get the old oring out(it is orange usually) the new filter should snap into place.....make sure it snaps in there or the filter will not function.......caution...