[R] error message in eval

[ckang2 at gmail.com]

Hello, Listers

I'm trying to run blloean logit model with R.

My code is:

> library(boolean)
> library(foreign)
> pr <- read.dta ("prcore1.dta")
> bp <- boolprep ("(a&b)|c", "cwt", a="O1", b="t", c="DM2
> + ah + md + con + n3 + rel + slo + pyrs
> + sp1 + sp2 + spl3")
> answer <- boolean (bp, link = "logit", method = "nlm")

But I got an error message here as follows:

Error in eval(expr, envir, enclos) : object "cwt" not found

"cwt" is my D.V. and I made sure that R read the data correctly.

It might be a stupid question.But, since I'm a very very beginner of
R, I don't know what's wrong.
I tried to figure out this with the manual, but I can't get any answer.

Could you anyone help me out?

Thank you very much in advance.

Best,
Charlie