Check your CSV file. There may be multiple reasons for the error.
One is that there is a line having less columns (commas) than the header. To detect this compare the number of items to those of the header:
if (dataWords.Length != headerLabels.Length)
{
}
Another is that the first line contains a comma within a quoted field. Note that such fields (quoted with comma) on other lines would make your code not work as expected even when the initial error would not occur.
To handle such quoted fields you have to use a more sophisticated method to get the fields from a CSV row. Search the net for something like "c# split csv row".
A common solution is to use a regular expression like
@"""?\s*,\s*""?"
and replace afterwards every two consecutive double quotes by a single one.