Hi there i am trying to set up an server using this guide Ubuntu home net server config

i get the error "Failed to save interface : An existing Ethernet interface must be selected for this bridge to use" at this part of the guide.

I will use for the purposes of this guide. This is the standard ip range to use for local home networks. Go to the "Interfaces Activated at Boot Time" tab and click eth_SAFE to configure it if it is there already. If it isn't there already (it probably isn't) then click "Add a new interface". Enter the following details:
"Name" - eth1
"IP Address" - Make sure the "Static" radio button is checked, and enter into the text box.
"Netmask" - Should be
"Broadcast" -
"Activate at boot?" - Set to yes

Any suggestions on how to fix it?