Sexpr not getting expanded in Sweave

An Sweave file, 'test.Rnw':

\documentclass{article}
\title{Sweave minimal}
\author{MK}
\begin{document}
\maketitle
We try Sweave:
<<1>>=
data(airquality)
summary(airquality)
x <- airquality[1, 1]
@

I try Sexpr: \Sexpr{x}

We plot:
\begin{center}
<<2, fig=TRUE, echo=FALSE >>=
boxplot(Ozone ~ Month, data = airquality) 
@
\end{center}
\end{document}

I check the sessionInfo:

sessionInfo()

R version 2.14.1 (2011-12-22)
Platform: x86_64-apple-darwin9.8.0/x86_64 (64-bit)

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] datasets  splines   utils     stats     graphics  grDevices methods   base     

other attached packages:
[1] cacheSweave_0.6     stashR_0.3-4        filehash_2.2        concord_1.4-9       irr_0.83            lpSolve_5.6.6       ca_0.33             rgl_0.92.798       
[9] vegan_2.0-2         permute_0.6-3       reshape_0.8.4       plyr_1.7.1          ggplot2_0.9.0       doBy_4.5.2          snow_0.3-8          lme4_0.999375-42   
[17] Matrix_1.0-3        lattice_0.20-0      multcomp_1.2-10     mvtnorm_0.9-9992    R2HTML_2.2          BiocInstaller_1.2.1 ctv_0.7-4           sos_1.3-1         
[25] brew_1.0-6          Hmisc_3.9-2         survival_2.36-12    MASS_7.3-17        

loaded via a namespace (and not attached):
[1] car_2.0-12         cluster_1.14.2     colorspace_1.1-1   dichromat_1.2-4    digest_0.5.1       grid_2.14.1        memoise_0.1        munsell_0.3        nlme_3.1-103      
[10] proto_0.3-9.2      RColorBrewer_1.0-5 reshape2_1.2.1     scales_0.1.0       stats4_2.14.1      stringr_0.6        tools_2.14.1      

and run Sweave:

Sweave(file = 'test.Rnw')

Writing to file test.tex
Processing code chunks with options ...
1 : echo keep.source term verbatim (label = 1)
2 : keep.source term verbatim pdf  (label = 2)

You can now run (pdf)latex on ?test.tex?

It works as it should except for \Sexpr

\documentclass{article}
\title{Sweave minimmal}
\author{MK}
\usepackage{Sweave}
\begin{document}
\maketitle
We try Sweave:
\begin{Schunk}
\begin{Sinput}

data(airquality)
summary(airquality)

\end{Sinput}
\begin{Soutput}
    Ozone          Solar.R         Wind            Temp          Month           Day      
Min.   :  1.0   Min.   :  7   Min.   : 1.70   Min.   :56.0   Min.   :5.00   Min.   : 1.0  
1st Qu.: 18.0   1st Qu.:116   1st Qu.: 7.40   1st Qu.:72.0   1st Qu.:6.00   1st Qu.: 8.0  
Median : 31.5   Median :205   Median : 9.70   Median :79.0   Median :7.00   Median :16.0  
Mean   : 42.1   Mean   :186   Mean   : 9.96   Mean   :77.9   Mean   :6.99   Mean   :15.8  
3rd Qu.: 63.2   3rd Qu.:259   3rd Qu.:11.50   3rd Qu.:85.0   3rd Qu.:8.00   3rd Qu.:23.0  
Max.   :168.0   Max.   :334   Max.   :20.70   Max.   :97.0   Max.   :9.00   Max.   :31.0  
NA's   : 37.0   NA's   :  7                                                               
\end{Soutput}
\begin{Sinput}

x <- airquality[1, 1]

\end{Sinput}
\end{Schunk}

We try Sexpr: \Sexpr{x}

We plot:
\begin{center}
\includegraphics{test-2}
\end{center}
\end{document}

The beginning of the .log file:
This is pdfTeX, Version 3.1415926-2.3-1.40.12 (TeX Live 2011) (format=pdflatex 2012.2.4)  23 FEB 2012 18:19
entering extended mode
\write18 enabled.
%&-line parsing enabled.
**test.tex
(./test.tex
LaTeX2e <2011/06/27>

Any thought? Please CC me when replying.

Michael Kubovy