I’m pretty sure you have to upload the image to Roblox and use the decal ID. If using the decal id on its own doesn’t work, put rbxassetid:// before the id.
Put the choices suggested in quotation marks.
I went to look up your error. It may be that you concatenated wrong. It would be easier if we could also see the exact code so that we could assist more.
My bad, I set a script. Well, I haven’t tested this yet, but if this doesn’t work then I will still have this as solution and find for myself the problem