On Wed, Nov 30 2016, ng0 wrote
> Is there anything obvious I have to change?

Your `let` body contains both the `(cuirass-service ...)` form as 
well as the `%desktop-services` form. A `let` form will take the 
value of the last form in its body, so the `(cuirass-service ...)` 
value is being thrown away.

Try removing one of the closing parentheses after `%desktop-services`
and add it after the `(cuirass-service ...)` form. (This has the effect
of moving `%desktop-services` out of the `let` body.)