Hi, I have a month long demo of Agisoft and am trying to learn now to create 3D models. I have photographed an object by rotating it 360 degrees with the camera at 4 fixed heights. For each new camera view, I took a photo of the background without the object so I could align the photos using the 'Apply masks to Tie points' feature. However when I go to align the photos the 'Apply masks to' drop down menu is greyed out and set to 'none'. Is this because I'm using a demo version or is there an easy fix? Thanks.