Chrome must be applied to a non-warm, platinum white base to display. Chrome is an ethereal silver and very delicate. When applied to a pre-platinum base it will produce a true Chrome colour. However, if someone with darker hair or a great deal of yellow uses the product, it will either be unable to display or attempt to act as a neutraliser.
Another factor is whether you clarified before application. If the surface of the hair was covered in polymers and residues, Chrome would simply be unable to enter to evoke change. Generally, though, it has been my experience that if you already have platinum hair – the product takes well upon initial application. The problems with the shade arise when those with a darker base or warmth attempt to use the product expecting to achieve that silver white result. Remember, Chrome is a Metallic Tone not a depth shade.