<t> ...<br/>
Starts distant worlds<br/>
<br/>
loads game<br/>
looks at design.<br/>
... [X(]<br/>
Epic facepalm.<br/>
...<br/>
edits design<br/>
orders invasion<br/>
Invasion valid<br/>
Pauses the game<br/>
Writes a post-it: "Never again create a troop ship design based on a passenger ...

<t> Hello everyone,<br/>
I'm seeking the help of experienced players as it seems I'm unable to invade a planet.<br/>
I suppose I forgot something essential but can't find what.<br/>
Thanks in advance for your suggestions[:)]<br/>
<br/>
EDIT: the answer was: In the design, "Invasion" must not be ...