I installed oracle universal installer ODAC1120320_x64 on wondows 2003 r2 x64. After the installation, I tried to connect to oracle database through cmd using sqlplus statement (SQLPLUS <username>/<password>@<tnsname>) and it was successful. then I tried to run a select query to test data retrieval but it returned no rows at all. I rechecked my statement, made sure it had no error and re run but again no rows was returned.
Then I tried to create a system DSN using the same tnsname but it failed and showed me an error before it could ask me for the password. Following is the error I received:
Unable to connect SQLState=IM003 Specified driver could not be loaded due to system error 127 (oracle in OraClient11g_home1).