the scenarion is like this...
I HAVE a namespace XXX
where I created some tables and some stored procedures...
THEY HAVE a namespace YYY<
I just had this same problem. I'm not a DBA but the way it was explained to me is "The basic thing is that your personal role privileges aren't in effect within the stored procedure."
I was advised to qualify the name of the SP with the owner of tables, like this:
CREATE OR REPLACE PROCEDURE yyy.PRC_PROC1( PARAMETERS... ) etc
This worked in my case in my dev environment. My environment only has one namespace so I'm not sure this will solve the OP's question but hopefully will help to move this issue forward for the next 18K people that look up this question ;-).
Also, when I put my SP into production, I will need to remove the qualifier and our installation software will run create under the proper authority.