So one of the most common problems witht he App Redirect and the App Store is the ability or should I say inability to use Host Headers. If you are using Host Headers within your web application its most likely not going to allow you to use the App Redirect.
App Redirect is how the App Store uses its functionality. So if you see a bad request error 400 it is highly suggested that you check your host headers and remove them.
When removing a Host Header from a Web Application I highly suggest that you follow this guide