Are the sims teens, or adults?
You can move out only adults, accompannied with teens; you can't move out teens alone - only to send them to college.
The process of moving out is:
1) sending the sim to the computer and order "find own place".
2) the sims just clicks on the keyboard, then stands up, the dialog which one goes with him appears, and his relatives run to him to say goodbye.
3) a taxi appears, and the sim goes to the taxi.
I don't know the answer for the missing dialog - I can only guess that the sim is a teen.
Does the taxi appear? If it doesn't - perhaps you should try the "carpoolfix" hack.
I hope JMP can help you with it...
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