wImage: How to tell if a SysListView32 table has an image or not?

I want to tell if a cell in my ListView32 table contains a wImage (code-jock checkbox) or normal text.

[See attached]

For text the object spy tells me that it is a (Null Object).

The watchList however tells me that ISNULL(listObj.wImage(row,col) is false- i.e. wImage is NOT NULL

but the watchList also says the listObj.wImage(row,col).EXISTS requires an object - i.e the wImage is a NULL OBJECT

How do I test in my VBScript whether a table cell has a wImage object or not?