Product:
Cognos Controller 10.1.1 (update version 10.1.6302.53-0)
Controller FAP client (version 10.1.6235.60-0)
Windows 2008 R2 server
Oracle database

Problem:
When try to login to the FAP database from the FAP client you get a error message
“Can’t connect to FAP database”.
same error as when you write the wrong password.

Solution:
Install oracle driver 11.2.0.4.0 64 bit version on the computer where you run the Controller FAP client.
Select to do a Administration client installation.

If you have the TNSNAMES.ORA file in a different folder than the normal for Oracle, then you need to update the Windows registry with this value.
Start REGEDIT.EXE
Expand HKEY_LOCAL_MACHINE – SOFTWARE – ORACLE – KEY_OraClient11g_home2
Right Click and select NEW – String Value
Set Value name: TNS_ADMIN
Set Value data: c:\orarun\tnsadmin
(the path to the folder where the TNSNAMES file are)