Cannot Run Inputbox Type 8 More Than Once In A Procedure

I cannot run the Type 8 inputbox (for user specified ranges) more than once in my procedure.

In the code below, the first inputbox for rngSource works fine, but clicking the ok button after selecting a range for the second inputbox (rngDest) pops up the following error:

Run-time error '424':

Object required

I initially thought that the Default option was to blame. So I created a dummy procedure with the command for the first inputbox repeated twice, and got the same error.

Sub InputBox_For_Ranges()
Dim rngSource As Range, rngDest As Range, rngStartingPoint As Range

Set rngStartingPoint = ActiveCell

Set rngSource = Application.InputBox("Select Source Cell", _
Type:=8, Default:=rngStartingPoint.Address)

Set rngDest = Application.InputBox _
(prompt:="Select Destination (SINGLE CELL ONLY)", _
Type:=8, Default:=rngSource.Offset(0, 1).Address)
End Sub