Cannot install iTunes 11.1 in MacBook

I've been trying almost daily for two weeks now to update my iTunes in my MacBook because I cannot sync my iPad (with iOS 7) to iTunes 11.0.5. I course the update through Software Update. I can get the update, and I agree to the terms, but then I get this message:

'The file "iTunesX.pkg" couldn't be found on the server "swcdn.apple.com".

What does this mean? Please help me....