Because the platform doesn't allow nested Table Records, List Records etc. You could try putting it in a web block. That said, in general it's bad user interface design if you need nested stuff like that.

No doubt there are good technical reasons, because of the complexity of having nested controls (web blocks wrap up scope etc. nicely), and the need doesn't that often arise.

Hi Tomasz,
This is indeed a tecnical limitation we have, and that is the main reason not to do this :( With platform 10, in mobile apps, we managed to remove this limitation and we allow List widgets inside Forms.

Out of curiosity, what kind of form were you trying to build?

Cheers,
Vasco Pessanha

Hi,
Let's say - a form with personal data and among them - a list of children.

Regards
Tomasz