Hi Gus, today I noticed there was another ompi directory in my path and maybe it gave some strange errors so I put the new ompi installation at the first place in PATH and LD_LIBRARY_PATH before the building and everything went nicely!
So, as you and Jeff said, the problem was in having the rigth paths! Thank you very much for your support! Damiano p.s. Building static libraries didn't result in any problem so far!