BlueValues and BlueScale in Private Dictionary

After I created superior and inferior numbers (not originally present) in a font to handle fractions, I receive the message:
`Alignement zone height in BlueValues/OtherBlues array is too big for BlueScale`.
So, the result is a uncorect Private Dictionary.
What exactly does it mean?
And what kind of action should I take to set the correct values?
Thank you