Haris,
Seems you are unable to restructure the component due to parent/child relationship. The component which you are using for restructure might be the parent for other components in assembly (assembled after that).
If this is true, there will be a warning "Attempts to append parent after child. Aborting restructure" in message area.
For example (referring image for carburetor.asm):
> Carburetor_plate.prt is in ASM0001.asm
> Other parts Bolt_5-60.prt and Air_filter_cover.prt are Children of carburetor_plate.prt
> When you will try to restructure Carburetor_plate.prt, it will report the warning, as restructure will try to move the part to bottom of model tree. As this part cannot place at the end of model tree due to child components, restructure will not complete the task and component will not move to top level.
Create another secnario for the same:
1. Create a new sub assembly at the end of this assembly.
2. Move Bolt_5-24 in that sub assembly. Now if if you will restructure, it will work without any warning or error.