If the planet with the 2.0 units out of range (this have nothing in relation if it connected to the dock or not ..) then you have only 1.5 units available and so to low ...
And i dont get your math ....
You musst have at last 1.0 units left at every planet ... and 1.0 in the colony ship ...
You have on with 1.5 - to low ..
And one with 2.0 - if it "in range" then you can get 1.0 unit out here ..
So where would you able to launch 2 ships with 1.0 each ???