400C True Transparent Issue

[GuestQ]

I have a problem in configuration FortiWeb 400C as a True Transparent Proxy. I' m unable to bind 3 interfaces to one V-Zone, web gui and cli shows error. But in manual here there is statement " Type the names of two or more network interfaces that currently have no IP address of their own, nor are members of another bridge" Second issue is that even if I use two interfaces i' ts imposible to add v-Zone without IP address. I have to write some random IP add that bridge. I' am doing something whong? Mayby there is some pre configuration steps? My FortiWeb version 5.0.4 but on 4.3.6. i have the same issue.