SQL & PL/SQL

I'm using Oracle Express 10g and trying to write/test a SQL script. It was working fine until I added more to it today. Now when I run it (in the SQL Scripts page), it just says status in Cancelled with no explanation & no results.

Looking at the script quota, it says 50,000 bytes, but the script is (according to the SQL Scripts details) 65,528 bytes. Although it doesn't complain about this when I upload the script (I edit it externally, as editing & saving from the built-in editor seldom works), I'm wondering if this is why it is Cancelling the run? Does anyone know how I can find out why it was cancelled?

According to the documentation (http://download.oracle.com/docs/cd/B32472_01/doc/appdev.300/b32471/sql_rep.htm) +"The size is set by the Oracle Application Express administrator and cannot be changed from within the Workspace"+. So how do I, as the Administrator, change the limit from 50,000 to, say, 70,000? I can't find any reference to how this is achieved, but the documenatation implies it is possible.

Please help, I need to get this script out quickly, it is for an important client!

Thanks
Martin