As mentioned elsewhere in the thread, the Starlab is only biome-specific in Low Orbit. Once in High Orbit, only one experiment can be performed, as expected.
Luckily, the automatic-experiment-resume feature seems to be working well in version 0.2.1, so you can fast-forward time to get tricky biomes like beach (takes several orbits, but eventually it's done).
P.S.: To see what region you are over, you can hover over the science icon on the left panel.