SSL Decryption - user bypasses http to https

I'm using cloud web security and I do not have SSL decryption enabled. I have a user being blocked on facebook, but when they go to https://facebook.com I though they would be able to have access since its encrypted, but instead I get the typical IE "Page cannot be displayed", as if it doesnt even see the url. Shouldnt I be able to browse it? Then when I have ssl decryption enabled I suppose it will be blocked withthe websense page, correct?

Thanks.