Board Game Arena

Beginner trying to learn the game in solo mode.

I can build the aviary, but not the reptile house (it's greyed out). Any idea why? (There is enough space on my zoo left, I did check that.)

In table https://boardgamearena.com/14/arknova?table=545399128, there is no space that accommodates the reptile house shape where it is adjacent to an existing building. If you use an additional X to perform Build action at 6, then you could place a 1-size building, such as a Pavilion, on the bottom right space with the 2 Reputation bonus, then build the Reptile House adjacent to it.

Thanks a lot. I thought I did check for that, but my brain registered my pavillon as an empty space.