Lua patterns returning nil

This match is returning as nil, even in my eyes is okay. string:match("^This boots belongs to the player (.-)%.$")

The string is

legendary boots. It can only be wielded properly by players of level 70 or higher. It weighs 8.00 oz. This boot has less regeneration than a soft boots, but it is infinite. This boots belongs to the player Administrador.

It should returns the player name "Administrador", but always return as nil. What I'm doing wrong?