Offtopic,I just saw the truncate table, I dont know the exact situation you are in, but did you check with global temporary tables.

Also you are using the full outer join, with inline views, I have had to deal with a similar situation with 9.2.0.3 and it still had problems inside procedures, I used row level security to solve it, metalink was of no help either. Try rls on employee_id and present.
The other way you can give a try is to have it as a view with a sys_context and se the context in your procedure.

Post your db version.

HTH
-dharma