Can't import R dump() data into JAGS, "unexpected LIST"

I used R dump() to create a data.txt file as specified by the latest JAGS manual, but I keep running into this error:

Reading data file data.txt
syntax error, unexpected LIST, expecting DOUBLE or NA or ASINTEGER or 'c'

The data.txt produced by dump(), from which I have removed the "L" assigned by R:

M <- 4
N <- 2
x <- structure(list(Var1 = c(0, 1, 0, 1), Var2 = c(0, 0, 1, 1)), .Names = c("Var1",
"Var2"), out.attrs = structure(list(dim = c(2, 2), dimnames = structure(list(
    Var1 = c("Var1=0", "Var1=1"), Var2 = c("Var2=0", "Var2=1"
    )), .Names = c("Var1", "Var2"))), .Names = c("dim", "dimnames"
)), class = "data.frame", row.names = c(NA, -4))
counts <- c(377558, 1001, 2000, 2000)
total <- 382559

If I remove x, the data will import correctly, but obviously that is not what I want. The strangest part is that if using the RJAGS and R2JAGS packages instead, the whole thing works fine. Does anyone know how to format this data to work in JAGS?

Solution

What seemed to fix this issue for me was a simple command per Martyn's suggestion on the JAGS board:

x <- as.matrix(x)