Topic: I can't tag myself as artist on my artworks

Hello, today I uploaded two of my 3D artworks and when I add in the tags "artist:digimonforever", I get the following error on top of the page in a yellow strip:

"<p>Tag type of "digimonforever" cannot be changed to "artist": You can not edit the type of existing tags using type prefixes, or the tag has more than 100 posts. Please review current usage of the tag and if you are confident the tag's type should be changed please use the Tags section of the website to change it.</p>"

I also tried adding a space between artist: and digimonforever, but then it'd appear like "artist -" on the "Artist" section of the tags and digimonforever as a tag below, which doesn't make sense.
I followed a thread from this forum to find the artist tag, but apparently it's not working correctly, or I'm not using it right.

Updated by NotMeNotYou