c# 4.0 - attempt to load oracle client libraries threw badimageformatexception -

i using visual studio 2012. installed oracle 64bit client. operating system win7 64 bit. want add new oracle db connection when enter username password etc. , click 'test connection' button, see error:

attempt load oracle client libraries threw badimageformatexception   problem occur when running in 64 bit mode 32 bit  oracle client components installed. 

but oracle client 64 bit. there no 32 bit component on system.

i having problem on oracle.dataaccess.dll added references. tried every combination cpu, x86i x64 platforms nothing has changed. everytime badimageformatexception.

i searched questions nothing has changed. tried iis app pool enable 32bit applications property true doesnt work.

any suggestions? else can try?