Privit Drive Safety Zone and Dobby

[uncmark]

No: HPFGUIDX 36716

I have a question about the supposed safety zone at No. 4 Privit 
Drive. According to Voldemort himself in GoF, he could not attack 
Harry at the Dursley's "Dumbledore invoked an ancient magic to ensure 
the boy's protection as long as he is in his relations care." GofF 
Ch. 33.

So HOW did Dobby get in in ChoS? Agreed, he didn't physically harm 
Harry, but he was able to intercept mail, cast magic on a pudding, 
and do some elf-magic equivalent of Apparation. Shouldn't the magic 
protect Harry from this?

Opinions?
Uncmark