The tutorial demo page does not make use of "addField". I suppose you are using the StockList demo page, which does take advantage of this method in order to add "extra fields", which are computed for each update, based on the other field values. The StockList demo uses extra fields to implement the arrows and as helper fields to implement the cell colouring.
Extra fields can be identified by names or by numbers; in the latter case, the numbers must be greater than the number of subscribed fields. Unfortunately, the StockList demo page code names the extra fields with numbers and uses the first numbers available (i.e. 14, 15 and 16). Admittedly, this is a bad choice and as soon as the number of subscribed fields is increased (which is your case), the numbers used are no longer allowed.
So, before adding the support for your new fields in the HTML page, you should change the numbers used in the various "addField" calls; you can use 114, 115 and 116, for instance. Note that the same changes should also be made in all places in which the extra fields are used, that is inside the "formatValues" method and in some cells.

Dario