There may be key conflicts occurred between original short-cuts and with the Aptana plugins.
Go to Window->Preferences. Type keys in the search box. Type Shift+Alt+Up in the keys preference page search box. If there are multiple commands registered then check the context of all these commands or assign new short-cut key.
!How to do this!
As you see in the picture. For Alt+Shift+Up keyboard short-cut multiple commands are registered. Change these short-cuts and make them unique.Click on Binding text box, delete the content and Hold your Ctrl key and Press 0.
Make sure that this short cut is not assigned to any other commands. Now you can do selection scoping using the new short-cut i.e Ctrl+0 while editing java source.