That type of error often means a data problem, for example dividing by standard deviation zero, or something similar.
Please look at your data values. Do you have enough items at each level of x that standard deviations can be calculated? ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
