[R] problem with a densityplot

[ch3o at autistici.org]

Hi,
i have a script how i launch lattice to make a densityplot.
in the script:

jpeg(file="XXX.jpg")
densityplot(~f_diametro+m_diametro+n_diametro, plot.points="rug",
auto.key=T)
dev.off()

does'nt work and in R i dont have any output
but if i launch by R row by row, runs correctly.....
any idea?