Calculating weir-fst by vcftools

Question

[Liangfa]

Hi, I'm using vcftools to calculate weir-fst, and getting confused by the result. One of the records is below, two populations, subpop1 and subpop2. I'm using a single SNP (Chr10:28041905) for an example. There are two alleles for this position, A and G. The allele frequency has also been calculated by vcftools. I got the WEIR_AND_COCKERHAM_FST of 0.63175 by vcftools. However, when I tried to calculated Fst by Fst = 1- Hs/Ht, it not equals the result of vcftools. And explanation will be appreciated.

POP       CHROM POS N_ALLELES   N_CHR   {ALLELE:FREQ}   {ALLELE:FREQ}
Subpop1 Chr10   28041905    2   220                      A:0.936364 G:0.0636364
Subpop2 Chr10   28041905    2   6686                 A:0.200718 G:0.799282

CHROM   POS WEIR_AND_COCKERHAM_FST
Chr10   28041905    0.63175