hi, I am a GATE User. I have sucessfully compiled GATE once, but problems comes when I try to recompile GATE in order to include the ecat and lmf features of GATE. it is ////////////////////////// src/GateCompressedVoxelOutput.cc: In member function 'virtual void GateCompressedVoxelOutput::RecordBeginOfAcquisition()': src/GateCompressedVoxelOutput.cc:97: error: incomplete type 'G4Material' used in nested name specifier src/GateCompressedVoxelOutput.cc: In member function 'virtual void GateCompressedVoxelOutput::RecordEndOfAcquisition()': src/GateCompressedVoxelOutput.cc:130: error: incomplete type 'G4Material' used in nested name specifier src/GateCompressedVoxelOutput.cc:131: error: invalid use of undefined type 'struct G4Material' /usr/local/geant4/geant4.8.1.p02/source/geometry/management/include/G4Region.hh:46: error: forward declaration of 'struct G4Material' /usr/local/CLHEP/include/CLHEP/Random/Randomize.h: At global scope: /usr/local/CLHEP/include/CLHEP/Random/Randomize.h:67: warning: 'CLHEP::HepRandomGenActive' defined but not used make: *** [/root/g4work/tmp/Linux-g++/Gate/GateCompressedVoxelOutput.o] Error 1 ///////////////////////////////// Could anyone give me some suggestion? Thanks a lot ,best wishes. -- Wang Zhentian Ph.D candidate Department of Engineering Physics Tsinghua University Beijing Address:Room 1424B Zijing Building.14# Tsinghua University P.R.China   100084 Dorm Phone：51538013 Lab Phone：62780909-86209 Cellphone：13520933699