Hi, Wile_E_Coyote.
Thank you very much for your quick reply. I assumed that the warning about the libraries were okay (as mentioned Warning in <TClass::TClass>). Do you mean that I should do gSystem->Load() in root with the library that I would like to load within brackets?
I tried this little piece of code and still get an error if I leave
TClonesArray *ParticleEnergy = new TClonesArray("ParticleEnergy");
in place. Is that my mistake then?