Wallpaper with df(hha) Function

I'm using df(hha) to change my wallpaper image. The function adjusts for the hour and AM/PM and the files are named correctly, but the wallpaper never changes/updates. Is there something I'm just missing? I have checked the file path for the images and it's perfectly copied and works when you use it to search for them. I just don't understand why it's not working as intended, even though the code does change.

First image is for the function and the context I'm using it, second is the image that's currently displayed, and third is the folder the images are collected in, the bottom right most image being the one that should be displayed.