The NaN may occur because the format for that column is numeric. That could be because you entered a numeric value for the property Data. You should enter a character value when you set up the table, e.g., for a 1-column table,
hObject = uitable('Data',{'whatever'});
If you later enter a numeric value, it will be converted to a string. If you don't want to specify an initial string, you could assign the column an empty string ('').
