[R] Sweave Error

[claudio.is at libero.it]

dear R users,

I am using sweave to generate report for my data analysis.
I recently updated R ro 2.8.0, and now I have the following results when compile the the tex file generated from R. 

This is pdfTeXk, Version 3.141592-1.40.3 (Web2C 7.5.6)
 %&-line parsing enabled.
entering extended mode
(./Lajos.tex
LaTeX2e <2005/12/01>
Babel <v3.8h> and hyphenation patterns for english, usenglishmax, dumylang, noh
yphenation, croatian, ukrainian, russian, bulgarian, czech, slovak, danish, dut
ch, finnish, basque, french, german, ngerman, ibycus, greek, monogreek, ancient
greek, hungarian, italian, latin, mongolian, norsk, icelandic, interlingua, tur
kish, coptic, romanian, welsh, serbian, slovenian, estonian, esperanto, upperso
rbian, indonesian, polish, portuguese, spanish, catalan, galician, swedish, loa
ded.
(/usr/share/texmf-texlive/tex/latex/base/report.cls
Document Class: report 2005/09/16 v1.4f Standard LaTeX document class
(/usr/share/texmf-texlive/tex/latex/base/size10.clo))
(/usr/share/texmf-texlive/tex/latex/amsmath/amsmath.sty
For additional information on amsmath, use the `?' option.
(/usr/share/texmf-texlive/tex/latex/amsmath/amstext.sty
(/usr/share/texmf-texlive/tex/latex/amsmath/amsgen.sty))
(/usr/share/texmf-texlive/tex/latex/amsmath/amsbsy.sty)
(/usr/share/texmf-texlive/tex/latex/amsmath/amsopn.sty))

! LaTeX Error: File `Sweave.sty' not found.

Type X to quit or <RETURN> to proceed,
or enter new name. (Default extension: sty)

who to solve the problem?

--
claudio