[Gate-users] problem during executing first step according to the user guide

[Shahla Razaghi]

Dear GATE users,

I am using Gate v6.1. According to the first step in the user guide, when I
input  "/gate/cylindricalPET/setMaterial Water" it shows
"src/GateMaterialDatabase.cc (l.126): GateMaterialDatabase: could not find
the definition for material 'Water' in material files" and closes the user
interface.
What is the problem related to? What should I do in order to solve the
problem?

Thanks
All my best
-- 

Shahla Razaghi
Medical Radiation Engineering
Faculty of Nuclear Engineering & Physics
Amirkabir University of Technology