You may be using the default OCCI libraries that are built with VS2010. Please check this:
You need to use the libraries that are compatible with VS2012. See the above link for their location.
I checked the path of the libraries. They are all correct. If they had not been, I think the project would not even compile.
I have two instances of Oracle running. The problem might come from that...
However, I abandon for the moment.
By the way, what is the exception thrown? Print the message. With whatever credentials you are using, can you try sqlplus? (sqlplus user/passwd@connstring)