Problem Building Tritetmesh

Hi

I followed the instructions in the INSTALL file but when I type scons in the tritemesh directory, I get the following even though tetgen and triangle have been installed:

scons: Reading SConscript files ...
/home/pietro/tritetmesh/scons/simula-scons
Using options from scons/options.cache
Checking for dolfin... yes
Checking for numpy-1... yes
Checking for python-2... yes
Checking for tetgen... no (pkg-config file not found)
 Trying to generate pkg-config file for tetgen... failed
Checking for triangle... no (pkg-config file not found)
 Trying to generate pkg-config file for triangle... failed
Warning: Unknown dependency package: tetgen
Warning: Unknown dependency package: triangle
scons: done reading SConscript files.
scons: *** No targets specified and no Default() targets found. Stop.

What could be the problem?

Pietro