Hello Nadam - might be a problem on the iPad 1, i.e. I'm assuming your iOS is at the maximum version possible w/ that old device (5.1.1. - current is 9.3.1) - you'll need to find an app that is compatible w/ the old operating system and will allow PDF annotation? Check this LINK for some recommendations, BUT you need to do the 'homework' to determine if the current offerings will work on your iPad 1? Dave