Unable to tick 'Is Active' on notification window

Hi,

I'm in the process of designing some new processes within a new module which has not yet been developed.  It is a clone of our virtually empty change module.

I have created my processes and so far all windows/processes etc.. have created and are currently under testing, however I have been asked to create an e-mail notification from one of the new processes.  I set up a notification window with all the required fields, added it to the process in the way I would within our incident module, however the Is Active? attribute is greyed out and will not tick.

Any ideas anyone?

Thanks,

Hayley