Dear Surf Ice developer,

I´m starting with Surf Ice and I really like the possibilities for visualization. I wanted to load sig.mgh results in surface but when I add overlay nothing appears. I tried to convert it into a .nii file but then it shows the message: error: no variability in overlay 0. Can you help me to visualize the results of a group comparison of cortical thickness in freeSurfer?

Thanks, 
Boris