I just launched my first few rockets. I built a space platform and launch some rockets with the building materials for the initial buildings there.

I was able to build foundations on the platform, but if I try to build anything else it only creates a ghost building. I have the required building materials for the asteroid collecter and the other buildings that are initially unlocked.

How do I actually start building stuff in space? What am I missing? What are the first steps to build a space platform?