flame of the forest why has it got white flowers and not red flowers this year?

The new leaves of Pieris flame of the forest are red fading to yellow, cream and finally green (I always thought they were bracts until I checked!) and racemes of white bell like flowers.. there is a Pieris with red flowers but not 'flame of the forest'

Do you mean that you have had the Pieris for several years and it had red flowers (Pieris japonica) and then suddenly, this year, the flowers are white?
If the plant is new to you and you have not seen it in flower before, then Moon growers answere is relevant.