New chickens not coming down from roost

Yesterday I bought a year-old breeding pair of Japanese Bantams. I want to keep them separate from my main flock. Their new housing is a kind of small aviary on our porch. It is actually similar to their housing at their previous owner's. Ever since I put them in there yesterday, the two of them have been sitting only on the highest roosts right under the ceiling and not come down to eat or drink, as far as I can tell. Food and water are at the floor of the aviary, also similar to their previous home. I eventually stuck a piece of bread through the grid next to them and the hen nibbled at it a bit, but nothing more. Then I held food right up to them and then lowered it slowly to the ground to show them - no reaction. They've been fasting for more than 24 hours now and since it's already dark here, gone to sleep in the meantime.
Together with them I bought an additional pet quality Japanese Bantam rooster whom I dropped into the main coop behind the house with my laying mutt hens (I know, one should quarantine... it just wasn't practical) - he was eating and drinking and seems to make friends rapidly with his new flock, they seem to like him, almost no squabbling. What's wrong with my breeding pair? Should I be worried or will they come out of it eventually? Any way I could help them?

I would go and put them gently on the ground to force them to face their fears and to show them the feed and water a few times a day, as well as to just to get them moving about.

@oldhenlikesdogs , thanks, they got over it. I didn't really dare to put them to the ground because they seemed terrified of my hands. But I did put some food on the lower boards and on the top of the nesting box. When I left for work in the morning, the rooster cautiously tried to climb down to reach the food on top of the nesting box. And in the evening when I came back, they had visibly dug their way through the sand on the ground and most of the food on the ground had vanished, also part of the water. They were back on their ceiling roost but at least they are no longer in danger of starvation ...

That's great to hear, poor little things have no clue what happened to them.