Where I type wrong???

Hello, world. I want to get correct SQL request of this (fig.1) contence. For proposes to solve this question I had created request inside request, and it works without fusion (fig.2). When I

tried to change constant value to my subrequest, I had fig.3. Where had I wrong? What syntax is he talking about?

Attachment 23546

That is what I was about to write )