You have to enable a feature:
In the client, the folder: game_things then game_things.lua and add it below the function load ()
g_game.enableFeature (GameSpritesAlphaChannel)
If you have already done this, the error is because your client is a version lower than 0.6.5 (most likely)
There is already a tutorial here in Xtibia:
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Grupo: Campones
Registrado: 18/06/15
Posts: 38
Reputação: +3
Gênero: Masculino
Hi, I have a problem I've added to your Tibia.dat Extending Transparency in after beating the game I have such a thing oco it?