[R] superimpose density line over hist

[Albert Vilella]

Hi all,

I'm trying to superimpose a rchisq density line over a histogram with
something like:

hist(alnlength)
lines(density(rchisq(length(alnlength), 4)),col="red")

But the rchisq line won't appear anywhere,

Anyone knows what I am missing here?

Thanks in advance,

    Albert.