I don’t think I can see an error in your screenshot? Only the confirmation box.
If everything seems as you want it to be (for ubuntumate to be displayed as the tag on the ubuntu-mate tagged topics instead) then press OK to make it so. 
I don’t think I can see an error in your screenshot? Only the confirmation box.
If everything seems as you want it to be (for ubuntumate to be displayed as the tag on the ubuntu-mate tagged topics instead) then press OK to make it so.