Use the companion app and Do it to debug your blocks, see also tip 4 here App Inventor: How to Learn | Pura Vida Apps
see also Live Development, Testing, and Debugging Tools
Why are you copying the image? This looks redundant as the following block converts the image and stores it at the new destination
Also I would do the Gallery Refeesh in the end
Taifun
Trying to push the limits! Snippets, Tutorials and Extensions from Pura Vida Apps by 
Taifun.