Can' Establish Endpoint

I have two servers both installed sql server.The name of the servers are A and B respectively.
The admin of sql server in A is 'domainuserA', and admin of sql server B is 'domainuserB'.


My purpose is create a mirroring for a database in server A, but i can establish endpoint in server A(network address can not be reached or does not exist), i have grant the 'connect to endpoint' permission to each login .




i past my code:

step1



Code Snippet
--Server A, principal
create database db_test
backup database db_test to disk='\sharefolderdb_test.bak' with init

create endpoint endpoint1
as tcp(listener_port=5002)
for database_mirroring
(role=partner)

alter endpoint endpoint1
state=started

create login [domainuserB] from windows
grant connect on endpoint::endpoint1 to [domainuserB]






step2



Code Snippet
--Server B, mirror
restore database db_test from disk='\sharefolderdb_test2.bak' with norecovery

create endpoint endpoint1
as tcp(listener_port=5002)
for database_mirroring
(role=partner)

alter endpoint endpoint1
state=started

create login [domainuserA] from windows
grant connect on endpoint::endpoint1 to [domainuserA]

alter database db_test set partner='TCP://A.corp.com:5002'


--step3



Code Snippet
----Server A, principal

alter database db_test set partner='TCP://B.corp.com:5002'


this step return a error message:

The server network address "TCP://B.corp.com:5002" can not be reached or does not exist. Check the network address name and that the ports for the local and remote endpoints are operational.







some wrong?

any suggestions would be appreciated.