Atlas2 mipmap levels

I am using the Atlas2 terrain system. The thing is that I can't get the highest mipmap level to be used. I have been creating a ground texture (dds) in different versions to experiment with with different number of mipmap levels. But i have found, no matter how many mipmap levels I have created, that the Atlas2 system always create the largest mipmap in the size of 128x128 pixels. Is this correct, or am I doing something wrong? How do I make the Atlas2 system use the higher 256 and 512 mipmap levels in my texture?