Jquerry condumb dumb.

IDs in an HTML document must be unique. Only one element in the document can have the ID Item, so $('#Item') (or document.querySelectorAll('#Item')) will only ever return a single element.

Based on your description, your table's ID is Item. If you call $('#Item').eq(1) you are asking for the second element in the document with the ID Item, which obviously can't exist.

I suspect you want something like:

$('#Item').find('tr').eq(row).trigger('change');

or

$('#Item tr').eq(row).trigger('change');

NB: If you have nested tables, this will not work properly; the rows of the nested tables will also be matched by the tr selector.

Assuming you've structured your table properly, you'll need:

$('#Item > tbody > tr').eq(row);