Dear SPM experts

I have 2 groups- patients and controls - one group (controls) very strong activation of the amygdala, FFA and occipital cortex during a fearful task. The second group- patients - nothing significant. Both analyses - one sided t-test in SPM12. 

Running Two-sided t-test shows no difference ! By all logic Controls vs Patients should have yield extensive significant results, and yet there is nothing significant - in both directions. 

Could anyone help me to understand this, and how to interpret the results. I have checked the data with ArtRepair for outliers, so nothing there to report...

THANK YOU  in advance 

Laura