how can be save the project that consist of the sub project?

how can be save the project that consist of the sub project?

Hi
as one project is constitute from several sub project when I create back up from the main project only the back up file has created is from the main project and as I restore it only the main project has restored and sub project that is subbranch of main project don't restored.
please look at the attach file for more information.
what's reason for this problem?

This is a migrated post! Originally posted on 06.03.2010 by user michael_k. Please be aware that information can be outdated.