Index Error
I receive this error when I spy a WPF object's "Items" property. What I think is happening is as you can see the datagrid on the left has no rows/records. Another datagrid previously opened did have ...
Forum Discussion
I think that by default, you are trying to access Item(0), which in your case does not exist yet. That's why it gives an Index Error, there are no Items, and therefore, no indexes.
Items.Count = 0
Items.Count = 0