avoid intersection of circles galapagos

Dear all,

I want galapagos to minimize the distance between different circles inside a square.

I created a line between some particular circles that have to be adjecent to eachother and asked galapoges to minimize the length.

I don't want the circles to intersect. I figured out a way to give a penalty to the gnomes that create when intersection apears but the problem still occurs. 

The problem is that the circles intersect and the lines between the circles can not be generated. so galapagos does not know what to do. 

Can anyone please tell me what I am doing wrong. It should be an easy problem to solve.