SQL Developer

I am trying to debug a simple pl/sql code using SqlDeveloper 1.5.1

Though I am able to get connected to the database, I get an error while establishing connection to debugger.

The error is thrown by:
Executing PL/SQL: CALL DBMS_DEBUG_JDWP.CONNECT_TCP( '11.111.11.111', '1528' ) --provide my pc's IP
Executing PL/SQL: CALL DBMS_DEBUG_JDWP.CONNECT_TCP( '22.222.22.222', '1528' ) --provide remote db's IP

This procedure takes 2 parameters:
1. IP Address: The error is the same if i provide my pc's IP address or the remoteDB's IP address
2. Port#: Port# 1528 is open, as it is the same port# mentioned in tnsnames file.
I have also got this confirmed that the port# 1528 is open from the networks team, and there is no firewall blocking the port# 1528.
and using traceart i am able to see the packets comming from the remote db 11.111.11.111 to my pc 22.222.22.222

I have also enabled Tools->Properties->Prompt for database host for debugging check box.

Supplying IP address of my pc: 11.111.11.111
Connecting to the database PBSD.
Executing PL/SQL: ALTER SESSION SET PLSQL_DEBUG=TRUE
Executing PL/SQL: CALL DBMS_DEBUG_JDWP.CONNECT_TCP( '11.111.11.111', '1528' )
ORA-30683: failure establishing connection to debugger
ORA-12560: TNS:protocol adapter error
ORA-06512: at "SYS.DBMS_DEBUG_JDWP", line 68
ORA-06512: at line 1
Process exited.
Disconnecting from the database Remotedb.


Supplying IP address of my pc: 22.222.22.222
Connecting to the database PBSD.
Executing PL/SQL: ALTER SESSION SET PLSQL_DEBUG=TRUE
Executing PL/SQL: CALL DBMS_DEBUG_JDWP.CONNECT_TCP( '11.111.11.111', '1528' )
ORA-30683: failure establishing connection to debugger
ORA-12560: TNS:protocol adapter error
ORA-06512: at "SYS.DBMS_DEBUG_JDWP", line 68
ORA-06512: at line 1
Process exited.
Disconnecting from the database Remotedb.

When my IP supplied is correct and the port# 1528 is open and exists, then why do i get this error?