Prompt to resume doen't work when modules are inserted as WebObjects?

Hi, I have a course with three modules. Each module need to work seperately in another condition, but they also need to present as a course and stored in an USB drive. So I create four story files for three modules and a 'Home' file which including these three module files as WebObjects. (Modules display in new browser windows) 

It works nice except one thing -- if users exit a module they won't be able to resume to where they left. I test the modules, it is ok to resume if I open them seperately(click each module's html file directly). But it won't resume if the module is opened as a WebObject. (The 'Home' file is ok to resume)

Does anyone can help me with this? How to prompt resume modules when they works as WebObjects? (modules need to be independent files, so I can't conbine them into a file.)