How did you install it? From an official binary package for your distribution or by compiling from source? In the latter case, you have to inform the system were the library are placed. You can either run (as root):
or from a user's point of view, add the following to your .bashrc (or any other configuration file if you run a shell different from /bin/bash):
if [[ -z $LD_LIBRARY_PATH ]]
this will update (or create) the LD_LIBRARY_PATH environment variable that lists all the directories where the executables can find the shared objects.