User's Topics

I have compiled a help project as a CHM help file, but when I enter a keyword on the Search tab, it does not find any topics in the help file despite the topics actually contain text that matches the keyword. So my question is: How do I enable the search function in my CHM file?

I've hidden a topic by selecting the "Hidden" option in the topic properties dialog. In the compiled help file, the topic is not visible in the Contents tree, but I can still access it via the Search tab. How can I fix this?