Connection to Oracle failed. OCIEnvCreate failed with return code -1 but error message text was not available.

Hi, All:

I am using the tool SQL Server Migration Assistant for Oracle to move an existing Oracle onto sql server. However, I can't connect to a source Oracle database from this tool, even though I can use PLSQL developer to do Oracle connection. I have googled Internet and follow suggestions to make security permission changes on Oracle client home page. Unfortunately, it is failed with the following error:

Please help me use SQL server instead of Oracle.

Oracle client home is: C:\app\oracle\product\11.2.0\client_1

Regards,