Error occurred during the pre-login handshake, Endpoint

Situation:
I created the customized SQL Endpoint for 3rd party vendor uses. I grant "Connection" permission for the account. Deny "Public" connect to Default [Tcp] Endpoint.
Turn on Firewall (ex: port 4999), Allow Remote Connection in SQL, Enable Tcp portocol, Name Pipe, SharedMemory. But it still showed the Error 64 even if the account was successfully established.

Solution:

I've tried lots methods to figure it out, but it still failed even I use sysadmin account with IP with local server. Finally, I'd try to drop the customized or rename the endpoint. So I went to the Blog below

• TCP listening ports and ENDPOINT ports behavior

http://blogs.msdn.com/b/sql_protocols/archive/2008/11/05/tcp-listening-ports-and-endpoint-ports-behavior.aspx

• ALTER ENDPOINT

http://ss64.com/sql/endpoint_a.html

They gave me an idea, why didn't I query the "EndPoint" status and port?

select name, port, is_dynamic_port, state from sys.tcp_endpoints

Then I fount the "Endpoint" is "STOPPED"
I knew the problem, so I login and type

ALTER ENDPOINT [YourEndPointName] state = started; --STOPPED

Successfully to login through the customized port....