Function throws error while using lapply, works fine otherwise - r

Question

I have a list containing data tables. A sample list can be created using following code.
mydata=read.table(textConnection("
MSA_id code variable Caucasian African.American Asian Hispanic Other
412 111011 1 64 2 0 0 0
412 111011 2 464 17 4 11 0
412 111021 1 2006 43 32 22 61
412 111021 2 559 18 6 10 0
412 111031 1 56 1 0 0 0
412 111031 2 1 0 0 0 0"),header=TRUE)
setDT(mydata)
z = split(mydata,mydata$code)
> z[1:2]
$`111011`
MSA_id code variable Caucasian African.American Asian Hispanic Other
1: 412 111011 1 64 2 0 0 0
2: 412 111011 2 464 17 4 11 0
$`111021`
MSA_id code variable Caucasian African.American Asian Hispanic Other
1: 412 111021 1 2006 43 32 22 61
2: 412 111021 2 559 18 6 10 0
I want to reformat elements of this list (data.tables) based on their values.
From my code, the elements of reformatted list should like this:
First Element:
[,1] [,2]
[1,] 64 2
[2,] 464 32
Second Element
Caucasian African.American Asian Hispanic
1: 2006 43 32 22
2: 559 18 6 10
Algorithm for this is:
Remove first 3 columns and the last column.
If minimum value of Caucasian is 0, or sum of minimum values of rest
3 (that is:African.American,Asian,Hispanic) categories is 0, then
set the element as NA.
Else if minimum of African.American is 0 or sum of minimum values of
Asian and Hispanic is 0, then sum up African.American, Asian, and
Hispanic as single category.
Else if minimum value of Asian is 0 or minimum value of Hispanic is
0, sum up Asian and Hispanic as single category.
Else keep the format as it is.
I created a function to do it. When I use this function on one element at a time, it works fine, but when I use lapply, it breaks.
formatTable <- function(z){
a = z[[1]]
b = a[,list(Caucasian,African.American,Asian,Hispanic),] # Deleting columns 1,2,3 and 8
if ( min(b$Caucasian) == 0) {
formatTable=NA
} else if ( (min(b$African.American) + min(b$Asian) + min(b$Hispanic)) == 0) {
formatTable=NA
} else if ( (min(b$African.American) == 0) | (min(b$Asian) + min(b$Hispanic)==0)) {
formatTable = cbind(b$Caucasian, b$African.American+b$Asian+b$Hispanic)
} else if ( min(b$Asian)==0 | min(b$Hispanic)==0) {
formatTable = cbind(b$Caucasian, b$African.American, b$Asian+b$Hispanic)
} else
formatTable = b
}
Using this function, t1=formatTable(z[1]) and t2=formatTable(z[2]) gives correct result, however if I use tbls = lapply(z[1:2],formatTable) it says Error in FUN(X[[1L]], ...) : object 'Caucasian' not found.
Please help on why lapply throws this error.