The catalogue Pantone® Formula Guide used in graphics, is printed by off-set system, therefore, if a different printing method is used (e.g.: flexographic), the employed colors will not have the same pigment type and tint strength.
The Pantone formula is a good starting point, however, it is essential to consider that the addition of a basic color rather than another is necessary to obtain the desired shade (as a rule, an addition of 10-20% in respect to the initial quantity).