Micros 3700 service charge config, “Enter Charge Payment“ message

[sfour_]

I'm setting up a tip/service charge. When the “Post to charged tip total“ setting is enabled, I'm getting a “Enter Charge Payment“ message when trying to add the tip to the check. When that setting is disabled, I don't get a “Enter Charge Payment“ message. My SIM script to apply the tip gets stuck at the “Enter Charge Payment“ message:

loadkybdmacro makekeys(1),key(1,458752), key(7,333),makekeys("2.50"),@Key_Enter,@Key_clear, @Key_Enter,@Key_clear

What is the “Enter Charge Payment“ message for? How can I modify the above code to get around that message?