ObjectBuilder - Change transparency option

[Oskar1121]

Hi everyone,
I've problem with ObjectBuilder, I'd change transparency option for my tibia.dat and tibia.spr files, but when I check the box and try to compile I got an error:

Error: Invalid sprite pixels length
    at otlib.sprites::Sprite/setPixels()
    at otlib.sprites::Sprite/set transparent()
    at otlib.sprites::SpriteStorage/compile()
    at ObjectBuilderWorker/compileAsCallback()
    at com.mignari.signals::Signal6/dispatch()
    at com.mignari.workers::WorkerCommunicator/inputChannelHandler()

I have no idea what's wrong, I mean I know but I don't know how I can fix it. Without transparency option files are compile correctly.