I have installed Oracle developer 10.1.2.0.2 in c:\DevSuiteHome_1 folder & installed oracel database 11g on d:\app\shah folder I can able to connect oracle using user name system & with password. but when i am trying to connect database using forms it gives me error ORA-12560 TNS:Protocol adapter error. I had copied tnsnames.ora & sqlnet.ora file from oracle folder (d:\app\shah\product\11.2.0\dbhome2\network) to developer folder (c:\devsuitehome_1\network\admin) My LSNRCTL Status is given below.... LSNRCTL for 64-bit Windows: Version 11.2.0.1.0 - Production on 24-APR-2014 20:44:29 Copyright (c) 1991, 2010, Oracle. All rights reserved. Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1522))) STATUS of the LISTENER ------------------------ Alias LISTENER Version TNSLSNR for 64-bit Windows: Version 11.2.0.1.0 - Production Start Date 24-APR-2014 19:07:57 Uptime 0 days 1 hr. 36 min. 36 sec Trace Level off Security ON: Local OS Authentication SNMP OFF Listener Parameter File D:\app\Shah\product\11.2.0\dbhome_2\network\admin\listener.ora Listener Log File d:\app\shah\diag\tnslsnr\Shah-PC\listener\alert\log.xml Listening Endpoints Summary... (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(PIPENAME=\\.\pipe\EXTPROC1522ipc))) (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=127.0.0.1)(PORT=1522))) Services Summary... Service "CLRExtProc" has 1 instance(s). Instance "CLRExtProc", status UNKNOWN, has 1 handler(s) for this service... Service "orcl" has 1 instance(s). Instance "orcl", status READY, has 1 handler(s) for this service... Service "orclXDB" has 1 instance(s). Instance "orcl", status READY, has 1 handler(s) for this service... The command completed successfully Please help me how to connect developer with oracle database Thanks in advance Mitesh