executing the "Enter =S_TAB1" you need a new screen command in order
to be able to set the field value.
GuiXT does not wait for the next screen when you execute an "Enter".
It processes all subsequent statements until it finds a "Screen"
command. Then it waits for the next screen to be sent by the SAP system and
continues the processing with this screen, or with the next matching one
(program + screen number).
script should read:
"=S_TAB1" // Order
V[FUNCTIONAL_LOCATION] "&F[Functional Location]"
F[Functional Location] "&V[FUNCTIONAL_LOCATION]*"
"=S_TAB4" // Operation