Vieler - 2012-12-22

I'm trying to make a simple script to produce a plot (let's say sin (x), it's not important). If I set up the script like the following

set preamble "\usepackage[T1]{fontenc}"
set preamble "\usepackage{lmodern}"
plot sin(x)

I get the error

Internal error: Could not find TFM file 'rm-lmbx10.tfm'. You may be able to fix this with a more complete installation of tex.

The problem is that I HAVE a complete installation of TeX: I have the proper TeX Live distribution downloaded from CTAN, not the always-not-updated Ubuntu version. Even more funny if I unset the preamble I get the same error but for the Computer Modern font!

Is there a way to make pyxplot undestrand this or to select simple ttf fonts from the system (but I'd rather use the TeX Live distro)? Otherwise, I'm not able to plot anything.

Thank you in advance.