There are two cases for this issue: it can be a limitation of the evaluation version of the software or you are using wrong image types to apply the masking functions.
Note: I have installed the application and all the functions are working just fine. Try to open a Bitmap image and then assign breakpoints. The Mask function is not available until all conditions are met. Press F1 and search for Mask because everything is explained in terms of Mask and Mask Transparency.