1. are you sure that you used the real bitaddress.org and not some similar looking website?
2. when you say saved it offline, you should have downloaded the source code from github not ctrl+s the website you had open in browser.
3. a private key can create multiple different types of addresses. make sure that you are deriving the same address type (checking the first character would be enough for starters. it would be "1", "3" or "bc").