SQL & PL/SQL

I have a global temporary table that is used within one stored procedure. Another procedure calls it twice in succession and the second time the child SP is called, the temp table is retaining the values from the first call. I want to clear the contents of the temp table before the child SP completes, but am getting an "invalid table name" error when I try to truncate it or delete the contents. Any thoughts?

By the way, when I created the global temp table, I used 'on commit delete rows'

Thanks
Matt