diff --git a/protopipe/aux/example_config_files/analysis.yaml b/protopipe/aux/example_config_files/analysis.yaml
index 67095ceb..8ea7f4cf 100644
--- a/protopipe/aux/example_config_files/analysis.yaml
+++ b/protopipe/aux/example_config_files/analysis.yaml
@@ -16,7 +16,7 @@ Calibration:
   # factor to transform the integrated charges (in ADC counts) into number of
   # photoelectrons
   # the pixel-wise one calculated by simtelarray is 0.92
-  calibscale: 0.92
+  calib_scale: 0.92
   apply_integration_correction: false
 
 # Cleaning for reconstruction
diff --git a/protopipe/pipeline/event_preparer.py b/protopipe/pipeline/event_preparer.py
index 6faa537a..e3ea5ca4 100644
--- a/protopipe/pipeline/event_preparer.py
+++ b/protopipe/pipeline/event_preparer.py
@@ -779,8 +779,14 @@ def prepare_event(self, source, return_stub=True, save_images=False, debug=False
                         ] = HillasParametersTelescopeFrameContainer()
                         n_pixel_dict[tel_id] = len(np.where(image_extended > 0)[0])
                         leakage_dict[tel_id] = leakages
+                        
+                        concentrations = {}
+                        concentrations["concentration_cog"] = np.nan
+                        concentrations["concentration_core"] = np.nan
+                        concentrations["concentration_pixel"] = np.nan
                         concentration_dict[tel_id] = concentrations
 
+
                 # END OF THE CYCLE OVER THE TELESCOPES
 
             # =============================================================