There were some changes to the data packets between X-Plane 10 & 11. The "sending data to X-Plane.rtfd" document in the instructions folder of X-Plane 11 includes version change info at the top:
NEW MESSAGES FOR X-PLANE 11:
ACFN this loads an aircraft with a new struct, documented in the list of messages below.
PREL this positions an aircraft with a new struct, documented in the list of messages below.
ACPR this loads AND positions an aircraft with a new struct, documented in the list of messages below!
DISCONTINUED MESSAGES FOR X-PLANE 11:
PAPT place by airport. use PREL now.
PMAP place by airport. use PREL now.
VEH1 move a single plane. use VEHX now.
VEHA move all planes. use VEHX now.
MENU select a menu. use CMND now.
CHAR select a menu. use CMND now.
MOUS select a menu. use CMND now.
ISET turn on or off an internet output. use ISE4 now.
ACFN OLD ACF struct with no livery. use ACFN now that is shown in the docs below, now with livery option.
HACF blow up an airplane. discontinued.
R_QT play a quicktime movie. discontinued.