julianms
If NI is specifying RHEL 6.3, I would go with that. Try to get that update, the Kernel you are looking for is this one
Typically with Linux, once you have a functional system you don't want to update the kernel, so I am assuming that NI tested it on RHEL 6.3 and it worked, so I would start by getting exactly the version of redhat mentioned above.
Good Luck!