Depending on the release of Oracle Client and the version of MSDev used to build oraocci??.dll you will have to use the same version of compiler to compile and link your application with occi dll. The release notes/document will have the compiler version.
I have tried with both oracle Instant client version 22.214.171.124.0 (Basic, sdk, sql), and oracle Instant client version 126.96.36.199.0(basic, sdk, sql). I added additional path for include directories in VC9 as SDK/Include, and SDK/lib/msvc/vc9 in lib path for additional libraries. But the code is throwing exception at p_conn = "p_env->createConnection(username, password, connstr)" in Debug version and at "p_conn->registerSubscriptions(sub_vec)" in Release version. I am really not able to understand where I am wrong, I am using windows 7 (32 bit) and Visual studio 2008. Can you plz tell me is there in any comaptibility problem in version of Install client I am using, if yes can u plz tell me which version should I use.
This for me looks like a setup issue only. Do you have any other Oracle Installations on the same host.
Pls check the directories in the environment PATH. For me it looks like its loading some wrong OCCI dll and not the correct OCCI dll built using VC9