I can't download YouTube app from icloud

I deleted the YouTube app about 3 or 4 months ago and I decided to download it again. I went to the App Store and I looked for it and when I saw it the iCloud icon was not there, so I clicked on the app in the App Store. The iCloud icon is dull and when I click on it nothing happens!!! I tried uploading YouTube from Safari onto the home screen but still it just takes me to the website not the app. I have a YouTube account and everything and I still get emails from YouTube but I can't download the app!!