how to have listview row colour to change based on data in the row

I followed this question stuck on changing each row color during run-time in listview in asp.net based on database entries and tried to do the same in VB but i am getting some unexplained errors, like Object reference not set to an instance of an object
most likely for this row =>
Dim cell As HtmlTableRow = DirectCast(e.Item.FindControl(“MainTableRow”), mlTableRow)

Accessing controls in the edititemtemplate of a listview

I am working with the listview control. By default I am showing the itemtemplate with an edit button. When the edit button is pressed the listview switches to the edititemtemplate. I need to populate one of the controls in the edititemtemplate based on the item being edited – I’ve tried accessing the control (via FindControl) in the ItemEditing event (and pretty much every other event as well), however the controls just don’t seem to exist. I can access controls in the itemtemplate ok, but not the edititemtemplate.