Alert based on group and node?

Hi there,

I am trying to create a new alert which i think should be pretty straight forward, and maybe i am being slightly dumb!

I have a group, which contains 8 servers, all running IIS. These web servers have an issue with their web application - you can tell there is a problem if the CPU hits 30% for longer than 3 mins. So I want to create an alert to send an email to the web team to let them know.

I open a new alert, choose group from the 'type of property to monitor' and then choose a simple condition - Group Name is <Mygroupname>

I then want to change the property type to monitor to node, and choose =- CPU Load is higher than 29

I set up the email etc, and save, all looks good. I then go back into the alert, and group name has changed to IOS Image Family

I assume this is because i am selecting out of 2 different property types?

Any help? is this possible?

Thanks