Picture Into FormView Image Object

In VB code of an ASP 3.5 page, I want to put an uploaded image into an image object on a FormView. My code looks like this:

FormView1.ChangeMode(FormViewMode.Edit)
Dim pictureIMG As Image = CType(FormView1.FindControl("Image2"), Image)
pictureIMG.DescriptionUrl = filePath & fileName

Where filepath and fileName are strings set equal to the correct path & filename on my local machine..

When I run the page on the local machine, I get this error message:

"Object reference not set to an instance of an object."

Any idea what I'm doing wrong?