Framepicture Not Working

Hi! So my server's software is PaperMC, and i've installed both the latest bukkit versions of FramePicture and Protocollib but whenever i use the command /fp set URL, it says an internal error has occurred? idk what i did wrong but any help would be appreciated! Thank you Also, I have no other mods or plugins that would interfere with anything.

https://mclo.gs/7hwUtCW

i actually just downloaded the image on map plugin which seems to be working great and does the same thing as framepicture! Thank u so much for the help tho!!!