problem with read.table

Any ideas why read.table complains about not correct number of elements in 
line
while readLine/strsplit indicate that all lines have the same number of 
elements ?

R

tbl <- read.table('tmp', header = T, sep = '\t')

Error in scan(file = file, what = what, sep = sep, quote = quote, dec = 
dec,  : 
        line 32 did not have 27 elements

lines <- readLines('tmp')
v <- 1:length(lines)
i <- 0; for (line in lines) { i <- i + 1; v[i] <- length(strsplit(line, 

'\t')[[1]]) }

v

[1] 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 
27 27
[26] 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 
27 27
[51] 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27 27

sum((v - v[1])^2)

[1] 0

length(strsplit(lines[32], '\t')[[1]])

[1] 27