Why doesn't this code work?:

Sub test1()
Dim ws1 As Worksheet
Dim ws2 As Worksheet
Dim rng1 As Range
Dim rng2 As Range

Sheets("Sheet2").Activate
Set ws2 = Worksheets("Sheet2")
Set ws1 = Worksheets("Sheet1")
Set rng1 = ws1.Range(Cells(3, 1), Cells(7, 1))
Set rng2 = ws2.Range(Cells(5, 5), Cells(5, 5))

When it gets to the "Set rng2 ..." line it give a "Runtime error '1004' ...."
It seems strange that it works for the "Set rng1" line without problem.

Also, I can't seem to find a good reference that will help me learn the
idiosyncracies of setting/naming ranges, worksheets, and workbooks.