App won’t work correctly when set to run at boot.

Question

Hi!

 

I've just created a simple app to auto retrieve pics from google and set them as the desktop wallpaper. It also can convert the image to jpg and copy it to the Pictures folder and stuff. When I run it either via VS or by directly clicking the program, it works all well. But when I set it to run at Boot, when I boot the computer, functions like "copy to Pictures folder" won't work. Anyone know why is that? I have attached the source code below.

 

Thanks.