You may encounter this kind of error in Apache error log :
Failed loading /usr/lib64/php/modules/ioncube_loader_lin_5.1.so: /usr/lib64/php/modules/ioncube_loader_lin_5.1.so: wrong ELF class: ELFCLASS32
This is because you are using the 32 bit IonCube loader on a 64 bit operating system! You need to use the proper version to get rid of this error and get it working.
You may find the suitable version for your system at the following address : http://www.ioncube.com/loaders.php