bibtex

Hi,
I am working with  winedt 5.5, Miktex 2.9 (32 bit) and win 7 (64 bit).
I use one or two bib files for all of my papers.
I write at the and of the paper
\bibliography{aaa}
for the file aaa.bib, as usual. The tex file is in another directory as the bib file, say the tex file is in the directory ttt, the bibfile aaa.bib is in the directory bbb\Bibtex. The directory bbb is added to the root of Miktex. But bibtex does not find the bibfile aaa.bib.
Everything is OK with Miktex 2.8 (32 bit).
Can anybody help me?
Best regards, Ferenc

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