The Epson One-Touch Action file does not work with Photoshop 6.
You need to record your own action to make it work with Photoshop 6.
The existing One Touch Script will work but you need a new action.
1. Click on the Action Tab in Photoshop 6 and delete the existing One Touch Action. If the action tab is not visible, select Show Actions from the Window Menu.
2. Select New Action from the Action pull down menu (little arrow to the right). Name the Action "Epson One-Touch" and click on the Record button.
3 Go to the File menu and select Epson Twain from the Import menu.
Select Stop Recording from the Action menu.
4. Press the One-Touch button on your Epson Scanner. It should work now.