Roota seems not to work fine with pythia6?

Hi rooters,

I am able to make a static executable “roota” using the command ‘gmake static’ and tried hsimple.C in tutorials, it went fine. But when I tried to use it (roota) in pythiaExample.C, still in tutorials, I got the following:

root [0]
Processing pythiaExample.C…
Warning in : class TAttParticle already in TClassTable
Warning in : class TDecayChannel already in TClassTable
Warning in : class TParticlePDG already in TClassTable
Warning in : class TParticleClassPDG already in TClassTable
Warning in : class TDatabasePDG already in TClassTable
Warning in : class TParticle already in TClassTable
Warning in : class TGenerator already in TClassTable
Warning in : class TPrimary already in TClassTable
Warning in : class TVirtualMCDecayer already in TClassTable

And after initialization is completed, I got the following errors:

********************** PYINIT: initialization completed **********************
Error: Can’t call TTree::Branch(BRANCHNAME,&particles) in current scope pythiaExample.C:124:
Possible candidates are…
public: virtual Int_t TTree::Branch(TCollection* list,Int_t bufsize=32000,Int_t splitlevel=99,const char* name=);
public: virtual Int_t TTree::Branch(TList* list,Int_t bufsize=32000,Int_t splitlevel=99);
public: virtual Int_t TTree::Branch(const char* folder,Int_t bufsize=32000,Int_t splitlevel=99);
public: virtual TBranch* TTree::Branch(const char* name,void* address,const char* leaflist,Int_t bufsize=32000);
*** Interpreter error recovered ***

Can someone tell me what’s wrong? I can not proceed to my study if I can not even run the tutorials/examples correctly.

Thanks and more power!

Sincerely,

Leo