Subset Quirk?

Hello All,

I am trying to subset a matrix using subset() and it works fine when I use
matrix notation, but doesn't work when I use established column names. 
Sample code is below:

library(mvtnorm)
library(sm)
library(ltm)
library(irtoys)

k<- 100
set.seed(271828)
t <-
rmvnorm(n=k,mean=c(-1,0,1),sigma=matrix(c(1,.8,.5,.8,1,.8,.5,.8,1),3,3)) 

colMeans(t)
var(t)
pairs(t)

#tview <-edit(t)

t1<-as.matrix(t[,1])
t2<-as.matrix(t[,2])
t3<-as.matrix(t[,3])

# write.table(t, file = "c:/ability.dat", sep = " ", row.names=FALSE,
col.names=FALSE)

N<- nrow(t)
id <- as.matrix(seq(001,N,1))

assign <- matrix(0,N,6)
assign[,1:3] <- t[,1:3]
  for (i in 1:N)
  {
    if (t[i,1] < 7) 
      assign[i,4]=1
    else 
      assign[i,4]=0
      
    if (t[i,1] < -1)
      assign[i,5]=2
    else
      assign[i,5]=3
      
    if (t[i,2] < 0)
      assign[i,6]=4
    else
      assign[i,6]=5
  }

group <- cbind(id,assign)
colnames(group) <-c("ID","T1","T2","T3","G1","G2","G3")

#  This command works fine...

g2 <- subset(group,group[,6]==2)

#  This command does not work...
g2 <- subset(group,G2==2)


Any thoughts?  

Oh, so Petr and Uwe don't cry:  R 2.5.1 on XP (SP2).