error : domainfile contains no nodes
 

Hello to all,
I'm trying to make a structured mesh by using ICEM about a 2D airfoil.
I pratically do all but there is a last problem :D:D
When i save the mesh ICEM gives me this error: domainfile contains no nodes.
I don't know what it means.
When I try to run it with Fluent, it gives me the same error: Error: Null Domain Pointer

I follow this tutorial and I also don't understand what the guys is doing from the minute 3:53. Maybe the error I made is in this part.
This is the tutorial https://www.youtube.com/watch?v=9Bc0NBk-urM