Jump to mission script

[Kami-sama]

My latest failed attempt:

do
SetQuestState("quest_16a", QUEST_DONE);
SetQuestLabel("CurrentQuest","18a");
QuestStart("mission_18a");
AddQuest("quest_18a", QUEST_PROCESS);
Long_Jump("earth");
end;

I try adding anything fitting I can see in the quest scripts. At least I know that the function is not executed by having the previous quest marked as complete.