please can you explain?

'your dream's boy'
i would be very grateful if someone can please explain why the phrase written above sounds wrong but is right grammatically? or if there is anythig wrong with it in the first place.
i ask because a boy appeared in a dream i had, the story of the dream was re-told in a short film, the actor who played the boy signed himself as 'your dream's boy' in an email.
please can someone attempt to explain.
thank you
Lorna

[2006]

'the boy in your dream(s)' sounds much better.