IA64 CI/DB and x64 App server issues

We are doing a platform upgrade of our 3.x BW system, moving it from a x86 platform to a IA64 platform. Application servers are x64. The issue we are having is after we upgraded Oracle to 10g/64 bit. Since this point we cannot get the application servers to connect to the database. At the point we brought over the system, 9i/32 bit, we were able to connect without issues. After 24hrs, I am a bit loopy and looking for a possible quick fix to get these servers up and running. Any help / guidance is appreciated.