TOAD - Privileges required for Debugging Oracle Procedure

The following privileges are required for debugger:
1. GRANT ALTER SESSION TO user_name;
2. GRANT CREATE SESSION TO user_name;
3. GRANT EXECUTE ON DBMS_DEBUG to user_name;

Minimum requirements to debug other than your own procedures, functions, and packages:
1. GRANT ALTER ANY PROCEDURE TO user_name; (compile)
2. GRANT CREATE ANY PROCEDURE TO user_name; (edit / save)

The following additional privileges are required for debugger inversion 10g and any version released after that:
1. GRANT DEBUG ANY PROCEDURE TO user_name;
2. GRANT DEBUG CONNECT SESSION TO user_name;

Also, verify that the DBMS_DEBUG package in the sys schema is valid.
After the above, EXIT and RESTART Toad.

References:http://rupamverma.blogspot.com/2010/09/toad-privileges-required-for-debugging.html