Themes not working on Irssi 1.4.5 (UbuntuMATE)

I want to set my theme to sfc1337 (on the Irssi theme page) on Irssi but after downloading it and moving it to ~/.irssi/, using /set theme sfc1337 just gives me the error "-!- Irssi: Theme sfc1337 not found". I can't find many questions on this online and the answers I have found do not work.