Error when segregating sites of vcf using vcfR::seg.sites "Error in latag2n(x) : no method for coercing this S4 class to a vector"

Question

I have a large vcf file from next gen sequencing. I am not able to segregate DNA sites using the seg.sites function.

I am able to load my vcf file using Discolor<-read.vcfR("file_name"), but when I try to find segregated sites in my DNA using seg.sites(Discolor) I get Error in latag2n(x) : no method for coercing this S4 class to a vector.

When I do class(Discolor), I get the following.

[1] "vcfR"
attr(,"package")
[1] "vcfR"