Can’t update critical update

What would keep me from being able to download the critical update for windows 98? The computer screen gets the message from Microsoft that it is checking my sytem and then when the critical update page comes up, I click the download button and I get nothing. I have had this trouble for about 2 months now, and would like to know what to check to get the download. I am not able to see my history of updates either, may be of the same proplem, could you give me any suggestions. Thanks Ed