That should be set to the pathname to the main document itself, not its directory.
Sorry, of course it is set to the document, not the directory. My fault.
Do you manage to get compilation to work, when the active document is not the main document but one of the children? If things are set up correctly, when you do that the main document will be compiled instead.
Yes, this is working fine. If I'm working on a children-document an I press Apple-R, the main-document is compiled.
Do you use any other mechanism to indicate in a child document, where the main document is, like %!TEX directives?
No, I just set the TM_LATEX_MASTER to the main document, that's all. (Both in the project prefs and the shell-variable in the TM-prefs). Could this be an error? Or are there over ways to set "master" and "children"?