Having submitted articles to several different journals of elsevier through the EES site, it seems that submitting a latex-based manuscript can be quite burdensome.
In detail, i always had problems in compiling and building the entire manuscript including figures and bibliography. Finally, i arrived to successfully compile and build a prospective article hence i would like to share the recipe of success :). In detail:
* Make sure that you are compiling and building your manuscript locally in your computer without errors. Although you may be able to produce a readable pdf on your computer, EES will not produce a pdf unless there are no errors in the compilation phase.
* Following the previous rule, at least in my case, implied that i had to use .EPS figures.
* Uploading a separate bibliography file (.bib) is not sufficient for EES. You have to additionally upload the corresponding .bbl file that should be produced if you can build your article locally. Eventually, both the .bib file and .bbl file should be designated as "Manuscript" files when uploading.
* If you are only using the style files that come along with the elsarticle package, avoid uploading them again in your submission.
That should be all :).