>>126760437
are you making sure you are measuring off the 12th fret? Are you holding the string down at first fret(or using a capo) while doing so?
That would be following the radius of the neck.
Are you holding the measuring card "straight up", when accounting for the radius?
if yes to all these, then you know, might be a high fret somewhere, get a feeler and check if you can stick them under any frets i guess.