How to debug "invalid subscript type 'list'" error in R (genalg package)

Question

I am new to genetic algorithms and am trying a simple variable selection code based on the example on genalg package's documentation:

data(iris)
library(MASS)
X <- cbind(scale(iris[,1:4]), matrix(rnorm(36*150), 150, 36))
Y <- iris[,5]
iris.evaluate <- function(indices) {
result = 1
if (sum(indices) > 2) {
huhn <- lda(X[,indices==1], Y, CV=TRUE)$posterior
result = sum(Y != dimnames(huhn)[[2]][apply(huhn, 1,
function(x)
which(x == max(x)))]) / length(Y)
}
result
}
monitor <- function(obj) {
minEval = min(obj$evaluations);
plot(obj, type="hist");
}
woppa <- rbga.bin(size=40, mutationChance=0.05, zeroToOneRatio=10,
evalFunc=iris.evaluate, verbose=TRUE, monitorFunc=monitor)

The code works just fine on its own, but when I try to apply my dataset (here), I get the following error:

X <- reducedScaledTrain[,-c(541,542)]
Y <- reducedScaledTrain[,542]

ga <- rbga.bin(size=540, mutationChance=0.05, zeroToOneRatio=10,
     evalFunc=iris.evaluate, verbose=TRUE, monitorFunc=monitor)
Testing the sanity of parameters...
Not showing GA settings...
Starting with random values in the given domains...
Starting iteration 1 
Calucating evaluation values... Error in dimnames(huhn)[[2]][apply(huhn, 1, function(x) which(x == max(x)))] : 
  invalid subscript type 'list'

I am trying to perform feature selection on 540 variables (I've eliminated the variables with 100% correlation) using LDA. I've tried transforming my data into numeric or list, but to no avail. I have also tried entering the line piece by piece, and the 'huhn' line works just fine with my data. Please help, I might be missing something...