Problems with bibliography generation

[Harold Mouras]

Dear Users, 
excuse if this is a silly question. I have A LyX file and a .bib file 
(attached). The bibliography option of the LyX document is set up on NatBib and 
the .bib file should be correct, but I cannot generate any bibliography.
Thank you very much for your help....
Best regards, 
Harold

example.lyx
Description: Binary data

Biblio.bib

Description: Binary data