Originally posted by Jean-Francois Briere: Hard to tell. Could be many things. You will have to tell us more about your problem.
Well, this is weird. The method's name was "cleanUp" (in Java) and when I changed it to "removeWindow" it found it! What's that about? It can't be a reserved name in C++ because in C++ code it was named "Java_MyClass_cleanUp" per the JNI rules.
They weren't very bright, but they were very, very big. Ad contrast: