ORA-29260:network error:TNS lost contact

Hi Experts,

i'm using utl_tcp in my code to open a connection then i enter the username and password, i put a loop in my code so i can send the commands to this connection using oracle pipes, but some times i got this error message, ORA-29260:network error:TNS lost contact, please i appreciate if some one tell me what is the problem is it a connection problem or a bug in utl_tcp package.

part of the code
.....
c := UTL_TCP.open_connection (remote_host=> Pipaddress,
remote_port=> Pportnumber,
CHARSET => 'US7ASCII');

-- login
ret_val := UTL_TCP.write_line (c,'LOGIN:' || Puser|| ',' || Ppass|| ';');
.........
LOOP
.........
RESULT := DBMS_PIPE.RECEIVE_MESSAGE (p_name);
DBMS_PIPE.UNPACK_MESSAGE (his_msg_cmd);
DBMS_PIPE.UNPACK_MESSAGE (his_msg_params);
.........
ret_val := UTL_TCP.write_line (c, his_msg_cmd || ':' || his_msg_params || ';');
.........
END LOOP;
.........
ret_val := UTL_TCP.write_line (c, 'LOGOUT:;');
UTL_TCP.close_connection (c);
........
END;