In what format to add a proxy in a proxy-cheker?
If you have public proxies (without login and password), then IP:PORT
If you have private proxies (with authorization on login and the password), then IP:PORT:USER:PASS
If proxy checked died please try again with only some proxy only.
You can get proxy list in proxy manager.
P.S.: If you have bought a proxy from us, then they are private!