diff --git a/mlair/run_modules/post_processing.py b/mlair/run_modules/post_processing.py
index 01f0d2d05d5810ac74c2aaecd09407a9d0c20289..62cc85edefbaede065d6a571531a13da2c04aac3 100644
--- a/mlair/run_modules/post_processing.py
+++ b/mlair/run_modules/post_processing.py
@@ -785,6 +785,8 @@ class PostProcessing(RunEnvironment):
 
             # test errors of competitors
             for model_type in remove_items(model_list or [], errors.keys()):
+                if self.observation_indicator not in combined.coords[self.model_type_dim]:
+                    continue
                 if model_type not in errors.keys():
                     errors[model_type] = {}
                 errors[model_type][station] = statistics.calculate_error_metrics(