Losing RTTI info after returning from a function

Given a class and subclass:

class Event {...}
class Note : public Event {...}

A Note is Cloned and stored in a pointer within a function f(). The type-information is preserved in the pointer and can be recovered by dynamic_cast:

void f()
{
   pEvent = pNote->Clone();    // create a clone of a Note
   ASSERT(dynamic_cast<Note*>(pEvent));   // check the pointer, here it works
}

Now, after returning from f() the type-information is lost:

f();
ASSERT(dynamic_cast<Note*>(pEvent));   // -> "Access violation - no RTTI-dat开发者_高级运维a"

The VS-debugger shows a valid pointer-value (unchanged), but not the derived class, other than while beeing in the f()-scope.

How can the RTTI-info for a pointer be lost when returning from a function?

There was a destructor accidently doing harm to the pointer. After removing this error, the RTTI works as expected.