SQL & PL/SQL

hi all,

First of all thanks a lot to everyone for always helping and guiding me through all the doubts i had asked here.I have leasrned a lot and appreciate your help.

So,my question is

executing the STORED PROCEDURE in Toad 9.0

execute assign_daily_plan('547615',null,null,'plan67063974107')

I am getting an error showing LINE NO. and ISSUE displayed.Now,when i cancel this ...it closes the window and execution over.

I am not at all able to debug any more in this case.where can i see the values getting printed out in the program and the values for the dbms.output lines.
I need to see all the inter-midate values during the run of the program till it gets the ERROR,possibly with BREAKPOINTS but...i am not able to do.Please help me

I use toad 9.0 to connect to Oracle 10g Database

* The stored procedure has dbms.output_lines for PRINT the flow of the program as well printing each variable data out during run time.
*Also,set SERVEROUT ON is at the start of the editor as well as I used all the buttons like "STEP OVER","STEP INTO","TRACE" as well SQLPLUS too