Access Null Confusion

Simple query using query design view.  I have with account name, account, ID

If I run the query asking if account is null it lists all of the results where there is no account number but where there is an ID

I want to say that if the account is null then make the value default to that of the ID.

I have done this thousands of times but for some reason it isnt working here.  

I have

IIF([Account] is null, [ID], [Account])

Simple but it returns no values

Thanks in advance for your help.