I used 2 transports to invade the Drengin home planet on the same turn, but seperately. The first transport took out approximately 5.6 billion. The second one didn't get as lucky but I ended up winning with only 34 troops remaining. However, after this supposed "successful" invasion, the planet still belonged to the Drengin. Is this a bug or do I need a sizable occuping army before the planet fall under my control?