Solution

MF Toolbox
1. Select where the document is placed in [Select Source].
(A): Select Source

ScanGear MF

In the Simple Mode Tab
1. Select where the document is placed in [Select Source].
(A): Select Source

In the Advanced Mode Tab
1. In [Original Input Method], select where the document is placed from [Platen Glass] or [ADF (1-sided)].
(A): Original Imput Method

WIA Driver
1. In [Paper source], select where the document is placed.
(A): Paper source