Hi,
Thanks to Gerry (see post [url]Collections in PROOF I found the solution. See there for details but basically what was missing in my code is the set of pragmas for the iterators. For example I had to add:
#pragma link C++ class TProofCollection<EventInfo>;
#pragma link C++ class std::vector<EventInfo>;
#pragma link C++ class std::vector<EventInfo>::iterator;
#pragma link C++ operators std::vector<EventInfo>::iterator;
#pragma link C++ class std::vector<EventInfo>::const_iterator;
#pragma link C++ operators std::vector<EventInfo>::const_iterator;
#pragma link C++ class std::vector<EventInfo>::reverse_iterator;
#pragma link C++ operators std::vector<EventInfo>::reverse_iterator;
to my newly created collection of EventInfo objects.
Cheers,
Isidro