diff --git a/mala/network/tester.py b/mala/network/tester.py
index 7c61b5c25..f7a9e7373 100644
--- a/mala/network/tester.py
+++ b/mala/network/tester.py
@@ -210,7 +210,7 @@ def __calculate_observable_error(self, snapshot_number, observable,
             target_calculator.read_from_array(predicted_target)
             predicted = target_calculator.band_energy
             return [actual, predicted,
-                    target_calculator.total_energy_dft_calculation]
+                    target_calculator.band_energy_dft_calculation]
 
         elif observable == "number_of_electrons":
             target_calculator = self.data.target_calculator