Colonizing Problem

Hi!

I'm running SEV 1.17. My empire started with Rock Colonization, but I have since researched Ice and Gas colonization. I built colony ships with the appropriate modules, defined the ships as the appropriate types, but when I attempt to colonize anything but a rock planet, I'm told "Cannot colonize ice" or "Cannot colonize gas". I'm using the right ships on the right planets... side note: the planets I thought I'd be able to colonize don't get the little red / green symbols saying I should be able to colonize 'em.

What up?

Thanks!