Why am I unable to to 'disable zone' in Delta configuration?

Hello there,

I have just followed a very clear and helpful tutorial at:

http://himerus.com/blog/himerus/omega-intro-2-delta-module-contextual-th...

I followed the step by step instructions as to how to create a template using Delta and disable specific regions in specific nodes within my site. However, my interface options look very different to those in the tutorial. I have attached two screen shots to show what I mean. I do not have any option to enable or disable regions. This is very puzzling. Can anyone shed some light on why this isn't an option for me?

Thank you so much in advance for any help offered. It will be gratefully received!

Martha