g2o in ROS creates problems with Csparse

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Hello everyone. I downloaded g2o library to use it from inside ROS. Everything seemed to work well, since writing

using namespace g20;

and including test library

#include "/opt/ros/fuerte/include/g2o/core/block_solver.h"

allowed compiling through rosmake from inside my package.
Problems arose when I started to write the real g2o code and just one line

SparseOptimizer optimizer;

caused the following error:

 /opt/ros/fuerte/include/g2o/solvers/csparse/csparse_helper.h:23:16: fatal error: cs.h: File o directory non esistente

Then I updated my system to have Csparse:

sudo apt-get install libsuitesparse-dev

but I got a message advising me that it's already there.
Finally, I modified my package's CMakeLists file:

include_directories(${CSPARSE_INCLUDE_DIR})

but nothing changed.
Does anyone how to solve the problem? thanks