The [Transfer] button does not appear until the printer is ready to print. (The [Save Transfer File] button remains displayed.)
Refer to the following FAQ and make the printer ready to print.
> I cannot print from my computer via USB.
When the printer becomes ready to print, open the [port] tab in the [printer properties] dialog box and make sure the [Enable bidirectional support] check box is checked. If it is unchecked, check it.