Anyone have any idea what this error message means?
Error in single.na(to) : argument is missing, with no default
Calls: mxModel -> mxPath -> generatePath -> single.na
I hesitate to post the script, 308 lines at present...
On line 74 of your script, I found the line to=c(,'CO21','CO22','CO23'). There's an extra comma before the 'CO21' in the call to c(). Believe it or not, "argument missing, with no default" is the error that R reports for this condition. I tried evaluating sum(c(,1,2,3)) and I got the same useless error message. I submitted a bug report to the R developers pointing out this was not a good error message. I pass the buck to the R team. In the meantime, when you get a cryptic error message you can use the command traceback() in R. After you get an error, using traceback() will produce a stack of the functions that were invoked up to point of the error. It's useful in determining where an error is occuring. Happy (bug) hunting.