ORA-02020: too many database links in use

I have created the 8 DB link but one DB link is not working below error

ORA-02020: too many database links in use

Solution:-

 [oracle@our12-test admin]$ sqlplus "/as sysdba"

SQL*Plus: Release 11.1.0.7.0 - Production on Tue Feb 8 12:31:05 2011

Copyright (c) 1982, 2008, Oracle.  All rights reserved.


Connected to:
Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> show parameter open_links;

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
open_links                           integer     4
SQL>
Solution:-
Stop your Database then edit init<$ORACLE_SID>.ora
add below line *.open_links=10 then start your database 

SQL> show parameter open_links;

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
open_links                           integer     10

SQL>

then my problem is resolved