Your ware is fairly thick. It was already vitrified in a previous firing. It now must climb and fall through quartz and cristobalite inversions during a decal firing. The firing schedule provided by the decal supplier ramps up very quickly. The result? A cracked piece.
This process is done by printing a design (using ceramic inks) onto a film coated decal paper, drying it, then transferring the film to the fired ware. But beware of problems.