Index numbering above 9 isn't working

Okay, I just came across a very strange phenomenon and I'm hoping someone can shed some light on it (or point out some obvious thing I'm missing :) ). I'm working on a rating form that has 11 numbered items wrapped in subforms. The subforms are rating[0] - rating[10].

Because LCD doesn't have an autonumbering feature, I created one using floating fields. Each rating subform has a description, and each description contains the floating field. In hierarchy view, it looks like this:

rating[0] //subform
autonum //floating field
desc //description field
comments

rating[1] //subform
autonum //floating field
desc //description field
comments

... etc., up to rating [10].

The autonum field contains this code to compute the correct item number:

$ = $.parent.index + 1 //adding 1 required because indexes are 0-based

Here's the bizarre thing. It works fine up to rating[8], where the autonum field displays "9" just as it should. However, the autonum fields inside rating[9] and rating[10] both display "0" instead of "10" and "11". So I messageboxed the name of the parents... and for the autonum field inside rating[8], the parent is rating[8], just as it should be... but for the autonum field inside rating[9], the name of the parent comes up as its own name...autonum!! Same thing for rating[10]. That explains the 0, but why aren't the parents showing up as rating[9] and rating[10] respectively? The subforms are structured identically.

Does anyone know if there is an LCD bug with index numbers 9 and above? Or does LCD insert a hidden node if an index number goes above 9? Any ideas how to compensate (other than hard coding the item number, which is exactly what I want to avoid? :) )

Thanks in advance--

Kathryn