I have PL/SQL Developer Version 11.0.5.1790 (64 bit) installed on my machine 64 bit windows 7.
In my database(Oracle database version 12c ) other schemas(app_user_2 and app_user_3) as well as my own schema(app_user_1).
I have rights to:
DBA_OBJECTS,DBA_SOURCE,DBA_TRIGGERS,CREATE ANY PROCEDURE,DEBUG ANY PROCEDURE
But whenever I start debugger to debug the code inside a package owned by app_user_2 or app_user_3, I can not step into the pkg.
When I F9 to start debugger, It just keeps executing.

To obtain some more diagnostic information, can you modify the shortcut and add the DebugSQL parameter? For example:

"C:\Program Files\PLSQL Developer\plsqldev.exe" DebugSQL

Reproduce the problem and send me the debug.txt file that is generated in the PL/SQL Developer directory or in the %APPDATA%\PLSQL Developer directory (e.g. C:\Users\<User>\AppData\Roaming\PLSQL Developer).

Have you added debug information to the package? You can check by right-clicking on the package in the object browser and see if the checkbox for 'Add debug information' is set. If not, set it and try again.

Marco : How would I send you the debug.txt file?
I dont see any option here.
If this emailid Marco Kalter (marco.kalter@allroundautomations.com) is of yours, I had sent you the dubug.txt on Mon 6/6/2016 12:18 PM in an email with subject Debugger issue with PL/SQL Developer Version 11.0.5.1790 (64 bit) but haven't got any response so far.
I am sending you the debug.txt file again.

Claus Pedersen: Yes ,I have added the debug info to package.