[R] PDF Corrupted?

[rkevinburton at charter.net]

I am running R 2.9.2 and creating a PDF that I am trying to open with Adobe Reader 9.2 but when I try to open it the reader responds with 

"There was an error opening this document. The file is damaged and cannot be repaired.:

I am using the R command(s):

pdf(file="cat.pdf", title="Historical Sales By Category")
for(j in 1:length(master))
{
    d <- as.Date(master[[j]]$Period[1], format="%m/%d/%Y")
    fit <- ets(ts(master[[j]]$Quantity, start=c(1900 + as.POSIXlt(d)$year, 1 + as.POSIXlt(d)$mon), frequency=12))
    plot(fit, col.axis = "sky blue", col.lab = "thistle")
    title(master[[j]]$Category,
          cex.main = 2,   font.main= 4, col.main= "blue")
}

Any idea what I am doing wrong?

Thank you.

Kevin