Error using cases (memisc)

I have this data example:

W1$age <- c(3,2,4,1,1,3,4,NA,2,NA)

I want to create a column where:

• 1 is replaced by 0

• 2,3,4 are replaced by 1

• everything else is NA

I have this code:

library(memisc)
W1$age2 =  cases( 
  "0"= W1$age == 1,
  "1" = W1$age == 2 | W1$age == 3 | W1$age == 4,
  "NA" = W1$age != c("0", "1", "2", "3", "4")
  )

it gives me this error (I googled it but I didn't find it):

Error in if (any(done == 0) && any(done > 1)) msg("conditions are neither exhaustive nor mutually exclusive") else if (any(done ==  : 
  missing value where TRUE/FALSE needed
In addition: Warning message:
In W1$age != c("0", "1", "2", "3", "4") :
  longer object length is not a multiple of shorter object length

I hope you can help me either to fix it with some alternatives, thanks a lot!