Why won't my garrison unit garrison?

[martinuzz (OP)]

I assembled 2 PDCs on a newly colonized planet, because the population was nagging about protection.
The 2 PDCs are identical, and each have room for a single batallion.
Now, I moved one garrison batallion into PDC 1, and that worked fine.
However, when I try to move the other garrison batallion into the other PDC, it does not work.

Is there a rule that only 1 PDC on a planet may be occupied by ground troops?

[Steve Walmsley]

I assembled 2 PDCs on a newly colonized planet, because the population was nagging about protection.
The 2 PDCs are identical, and each have room for a single batallion.
Now, I moved one garrison batallion into PDC 1, and that worked fine.
However, when I try to move the other garrison batallion into the other PDC, it does not work.

Is there a rule that only 1 PDC on a planet may be occupied by ground troops?

No, you should be able to move troops into multiple PDCs. In my current game, the Chinese have ground forces in several different PDCs. Make sure you have the correct PDC selected when you click the Transfer button on the Ground Units tab of the F2 window.

Steve