The JVM was unable to load the native wlfileio library , on Linux

We are getting this message:

<Warning> <Store> <BEA-280109> <The JVM was unable to load the native wlfileio library for the store "bla". File and paging stores will continue to function correctly. Specifically, file stores that are configured with a transactionally safe synchronous write policy will continue to operate safely and transactionally but may open with a different write-policy. Other store types may not be able to open.> 

http://docs.oracle.com/cd/E21764_01/apirefs.1111/e13952/pagehelp/Corecoreserverserverconfigservicestitle.html#attributes under Synchronous Write Policy it explains a lot
Your default-file-store or file-store should be using in the LD_LIBRARY_PATH env variable one of the following folders / files (LD_LIBRARY_PATH should point to a FOLDER only, not to a specific FILE):
WL_HOME/wlserver/server/native/linux/x86_64/libwlfileio3.so WL_HOME/wlserver/server/native/linux/i686/libwlfileio3.so WL_HOME/wlserver/server/native/win/32/wlfileio3.dll WL_HOME/wlserver/server/native/win/x64/wlfileio3.dll WL_HOME/wlserver/server/native/solaris/sparc64/libwlfileio3.so
Check the java.library.path which should also be initialized to the same value.
Otherwise, run weblogic with strace to find out what is going wrong
See also http://mcgmiddleware.blogspot.ch/2012/03/weblogic-on-linux-x86-64-libmuxer.html and see http://blog.whitehorses.nl/2012/05/30/native-io-in-weblogic-on-solaris-11-x64/
Check also that you are using the 64 bit JVM and not the 32 bit