uscn.id = 100*(lexrates.dat[,"USCNF"]-lexrates.dat[,"USCNS"])

uscn.id.dm = uscn.id - mean(uscn.id)
arma11.mod = list(ar=0.75,ma=0)
arma11.fit = arima.mle( uscn.id.dm,model=arma11.mod)
arma11.fit

Then on page 80, plot(arma11.fit) encounted the problem, only the first residual plot is given, and error msg displays as:

> plot(arma11.fit)
Problem in attr(object, "na.message") <- paste("Dropped", length(nas), "cases..: replacement using function "attr" not defined for non-vector class "timeSeries"
Use traceback() to see the call stack