If you are zipping the folder by right clicking and choosing "compress" from the contextual menu, then your zip will have the wrong structure and when you attempt to install it on the Roku, you will see an error on the debug console telling you it can't find your source directory.
The structure needs to be channel.zip/source, not channel.zip/channel/source. One way to be sure you are zipping the channel correctly is to use the Makefile included in the SDK.
If you have the correct structure and the channel does not appear on the Roku home screen, there may be syntax errors in your BrightScript. These will also be called out on the debug console when you install the channel.