This is our problem (extracted from What is the natural start order for package-dependent OSGI bundles (under Karaf)? - Stack Overflow):
In OSGi the bundle lifecycle is installed -> resolved -> starting -> started. Import-Package and Export-Package only influence when the bundle goes from installed to resolved. So the framework makes sure all bundles you import packages from are resolved before your bundle but then your bundle only goes to the resolved state. Then in a second step the activators are called. So you can not assume the activators are called in the same order. If you need some initializations before [...] then you should use OSGi services.
SCR replaces the old-fashioned Activator classes.