When installing the ODBC driver to a Windows 2008r2 server. I got the Error Code 126.
Make sure the ODBC driver config. is OK.
I installed the OracleInstant x32 drivers, side by side the x64 driver on 1 machine.
Which is needed in case you work with the Report Builder 3.0, which is 32bit.
While the SSRS in SharePoint integrated Mode is using the x64 bit drivers.
Set the Environment Variables correct.
Set the proper Security to the folder where the driver is residing.
SSRS Test the new driver configuration
But restart the SSRS services before testing.
All working fine now