如何在列表视图中获取所选行上方和下方的行内容？

I am getting an error intermittently with my listview when I click on a row in order to delete its contents and merge the contents of the above and below rows into one row. when I use the code in another part of the program it works but for some reason it gives an error here in the code I list below. Is there a way to get the code from the above and below rows of my selected row in listview?I am getting an error intermittently with my li