The virtual keyboard on an E600 might not be enabled. If this happens you will not be able to enter data into any fields, because the keyboard won't come up when you tap any box. But it is easy to enable the keyboard in these instances.
While in an active field on the POS application, press the keyboard icon in the bottom right corner of the screen.
Check Show Virtual Keyboard. Now when you select a field, the keyboard will automatically come up.