Is the path of the library in your LD_LIBRARY_PATH envrionment variable?

Is the path of the library in your /etc/ld.so.conf file? If it isn't, add it to the file and then run 'ldconfig'.

Type "ldconfig -v | grep libclntsh" and see what comes back, post it if you want.

Sometimes everything seems correct and the library still gives an error, I suppose something isn't correct but it's not always easy to find. Try those first steps first and let me know what happens.