"Jumping is not allowed here."
Translation:Здесь прыгать нельзя.
"Прыгать нельзя здесь"
Is there a reason why this is not accepted?
"To jump is not permitted here" seems like an acceptable word order.
It is rather weird. General permissions usually state where it applies, then say нельзя or можно, then put the infinitive. So, «Здесь нельзя прыгать» is the most neutral word order of all, and «Здесь прыгать нельзя» or «Прыгать здесь нельзя» also work with the emphasis slightly shifted.
Simply because there are more common word orders that you have to master first.
Yeah, especially about that. Probably, «Нельзя прыгать здесь» and «Прыгать нельзя здесь» are the most unnatural of the six possible word orders which I can hardly imagine a native speaker ever say. Нельзя здесь прыгать is kind of borderline case. We have to draw a line somewhere and stay more or less consistent with which word orders we consider passable and which we do not.