That works fine! Thank you ToothpasteBruva!

I've never been working with blender or blend4web, so that could be a really easy question. I just want to make a keyframe animation with three objects. Each of them should become visible at a certain frame. In the editor it works fine. I just changed the "eyeball" and "camera" icons on and off at the keyframes, pressed play and it played the result I wanted to achieve. But when I export it as html those changes on the "eyeball" and "camera" icons have no effect ( other changes, for example changing the location values are working and are producing an animation in the exported html). All the objects are visible in the html already at startup.
How can I achieve a working animation in the html with objects that are invisible at start and become visible at a certain frame? (The "Apply Default Animation" is already on)