[R] Installation problem with package mixtools

[David]

I am trying to install mixtools on Debian Etch and get the following error

dell-2 /usr/lib # R CMD INSTALL mixtools_0.1.0.tar.gz
* Installing *source* package 'mixtools' ...
** libs
gcc -I/usr/share/R/include -I/usr/share/R/include     -fpic  -g -O2 -std=gnu99 -c new_svalues.c -o new_svalues.o
gfortran   -fpic  -g -O2 -c sphericaldepth.f -o sphericaldepth.o
make: gfortran: Command not found
make: *** [sphericaldepth.o] Error 127
ERROR: compilation failed for package 'mixtools'
** Removing '/usr/local/lib/R/site-library/mixtools'

I have upgraded my installation of libgfortran and have added /usr/lib
to PATH but the error persists.

The same file has installed perfectly on a similar machine. I am not
sure how to proceed from here.

thanks
Dave