I tried that very same address. I put in the captcha, I imput the password, it "loads" for a moment and
always responds with "connection rejected", or something like that. So now I'm stuck.
https://www.reddit.com/r/Bitcoin/comments/35ohpn/trying_to_import_a_dat_wallet_onto_blockchain/ so you should either try contact the blockchain support like they said , or try also what someone suggested , download Bitcoin Core , put the wallet.dat on the right directory while it's sync with the network , dump the private keys using commands on console and you can import them to Electrum or any other wallet later (you can do it for blockchain.info too but if you do that , don't keep them for too long , not secure to keep coins online)