aboot with hierfstat::fstat

[ghost]

I've been trying to use aboot with hierfstat's fstat with little success.
Following are the commands I used from a clean environment:

install.packages("poppr")
install.packages("hierfstat")
library("poppr")
library("hierfstat")
data("nancycats")
my.fst.dist <- function(s) fstat(x = s,pop = NULL,fstonly = TRUE)
nancy_tree <- aboot(nancycats, distance = "my.fst.dist")

This gives the output:

Error in fstat(s) : x is not a valid genind object

However I also get the following:

nancycats

/// GENIND OBJECT /////////

// 237 individuals; 9 loci; 108 alleles; size: 145.3 Kb

// Basic content
@tab: 237 x 108 matrix of allele counts
......

and

fstat(nancycats)

gives

         pop       Ind

Total 0.08494959 0.1952946
pop 0.00000000 0.1205890

Any help would be appreciated.
Thanks,
Will