Question about TGenPhaseSpace

Hi, I have a question about TGenPhaseSpace. I want to modify the code, and I just tried the first thing, which was just to copy the original and change names. in some other part of your website I found that in order to implement my own clases

ClassDef(ClassName,ClassVersionID)  //The class title

and also

ClassImp(ClassName)

must be in the .C and .h parts of the code.
When I run my code trying to use the copied version of TGenPhaseSpace I get this

IncrementalExecutor::executeFunction: symbol '_ZN6TMyGen8GenerateEv' unresolved while linking function '_GLOBAL__sub_I_cling_module_4'!
You are probably missing the definition of TMyGen::Generate()
Maybe you need to load the corresponding shared library?
IncrementalExecutor::executeFunction: symbol '_ZN6TMyGen8GetDecayEi' unresolved while linking function '_GLOBAL__sub_I_cling_module_4'!
You are probably missing the definition of TMyGen::GetDecay(int)
Maybe you need to load the corresponding shared library?
IncrementalExecutor::executeFunction: symbol '_ZN6TMyGen8SetDecayER14TLorentzVectoriPKdPKc' unresolved while linking function '_GLOBAL__sub_I_cling_module_4'!
You are probably missing the definition of TMyGen::SetDecay(TLorentzVector&, int, double const*, char const*)
Maybe you need to load the corresponding shared library?

Thanks for your help

Being followed in another entry, closing.