I have seen the `RedirectionStatus.CanNotRedirect` pop up when the app fails to set up the SharePoint client context correctly. This can happen when the query strings are not set properly (or at all). 

Your app part requires some info, such as the `SPHostUrl`, that are passed to your app part from SharePoint via the query string. It looks something like this:

    

> ?SPHostUrl=http%3A%2F%2Fmy%2Dsp%2Dsite&SPHostTitle=My%20SP%20Site&SPAppWebUrl=""&SPLanguage=en%2DUS&SPClientTag=0&SPProductNumber=15%2E0%2E4569%2E1000&SenderId=ABCDEFG

Since you say it works fine until you click the button, my suspicion would be that these query parameters are not getting passed back to your app with the postback. Can you check if that is the case?