How do I operate the improved melting plant, everything I do on it isn't working?

Debe poner en los huecos de 4 casillas los 3 materiales que le pide y carbón, también debe poner carbón en combustible y empezará a fabricar.

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He must put the 3 materials that he asks for and coal in the holes of 4 squares, he must also put coal in fuel and he will begin to manufacture.