I have this simple code which will not run. Any thoughts would be much appreciated.

library(Rgraphviz)
main <- function() {

    dotFile <- agread("/Users/MACKLORI/sterling/genealogy/test.txt")
    plot(dotFile)
}

main()

reading this simple dot file
Digraph A {
    A [label = ”G”];
}

When I run this code in RStudio, I receive "R session aborted", "R encountered a fatal error".

Here are the version details

platform       x86_64-apple-darwin15.6.0   
arch           x86_64                      
os             darwin15.6.0                
system         x86_64, darwin15.6.0        
status                                     
major          3                           
minor          6.1                         
year           2019                        
month          07                          
day            05                          
svn rev        76782                       
language       R                           
version.string R version 3.6.1 (2019-07-05)
nickname       Action of the Toes