Advanced Search - Does NOT show ALL Documents

Hi All.

Happy New Year to Everyone.

I  am doing an Advanced Search using the Search Center I created and noticed that when I searched for a document name, that I know I have one in one site (in minor revision (4.1)) and another document with the sane name in another site (in major revision (2.0)), the search result only show me 1 result.

Any idea why?

I know that when a do a search using the search at the top right corner in the site, it does pick up the same document that it didn't pick up with the Advanced Search.

Thanks for you help.