Connect vapor barrier film to Ytong masonry

Hello everyone,
Can I stick the vapor barrier foil directly onto a Ytong masonry or do I have to apply a smoothing coat first?

Thanks for your help.

You can do it, but it's like trying to seal something against a chain link fence.

Thank you very much for your reply. Can I then simply make a slurry with tile adhesive? Is priming necessary or not? Thank you in advance.