How do you get 20+ rows

I've been trying to figure this out,, but I cant, so I 'm wondering, How do you add more than 20 rows. And changing the row number to anything above 20, wont let it work. I need at least 100 rows, is that possible? Thanks.

Set number of rows like this
// set number of rows/columns
obj.setRowProperty("count", 100);