I've tried and tried to set this up, I thought I'd successfully done it but it still isn't working. This is what I did for three ad networks.
I created a header and footer advert in inventory. I then created an order for Network #1, followed by two adverts (one header, one footer) as line items for Network #1.
I then created an order for Network #2, followed by two adverts (one header, one footer) as line items for Network #2.
I then created an order for Network #3, followed by two adverts (one header, one footer) as line items for Network #3.
For all adverts the settings were price priority, end time unlimited, limit none, display creatives one or more, rotate optimised. All these were left as default apart from type which I set to price priority as I wanted Network #1 to appear first, but I had hoped the others could also appear if Network #1 couldn't deliver. But this didn't work.
For rate, network #1 was the highest at 0.75. Network #2 was 0.60 and Network #3 was 0.50.
Only network #1 is showing as delivering, the other two have stayed as Ready for 3 days, and simply will not deliver. Clearly I've done something wrong and price priority isn't working as it is ignoring Network #2 and #3 completely.
Can anyone help?