Reinforcements button greyed out...

I'm playing the rebels campaign, and im as far as the vergesso asteroids, but now it doesn't matter what planet I go to, I can't call in reinforcements, the button just continues to be greyed out so i die really fast cause i only have like 6 troops to battle tanks with... The game has worked fine until this point, not sure if I'm doing something wrong or if it's an actual bug.