Error Loading Shared Libraries when Installing Redhat Directory Server

Is dsktune a 32-bit or 64-bit executable? Whichever it is, you need a matching libstdc++.so.5. You seem to have two libraries for version 6 but only one for version 5; presumably you have version 6 for both architectures but version 5 only for the other architecture. Install compat-libstdc++ for the architecture that dsktune is for.

When you do:

ldconfig -v | grep libstdc

will you see a libstdc++.so.5? Or did you run ldconfig after installing of compat-libstdc++ package?