R help - Feb 2008 - Error with stop()

Hello;
I've used stop() previously without any problem.
Now, I'm using a condition and getting an error when stop() is called.

Mi condition is:

if(dim(r.temp)[1] != (length(jul.names)+6)) stop("buffered data not
available")


An the R' response is:
> source("my_program.R")
Error in eval.with.vis(expr, envir, enclos) :
  buffered data not available
>
Can you help me with this?

Best regards,
Javier