diff --git a/scenarionet/examples/run_scenario.py b/scenarionet/examples/run_combine_scenarios.py
similarity index 68%
rename from scenarionet/examples/run_scenario.py
rename to scenarionet/examples/run_combine_scenarios.py
index 8d5f97f..75d5039 100644
--- a/scenarionet/examples/run_scenario.py
+++ b/scenarionet/examples/run_combine_scenarios.py
@@ -2,11 +2,19 @@ import os
 
 from metadrive.envs.scenario_env import ScenarioEnv
 from metadrive.policy.replay_policy import ReplayEgoCarPolicy
+from metadrive.scenario.utils import get_number_of_scenarios
 
 from scenarionet import SCENARIONET_DATASET_PATH
+from scenarionet.builder.utils import combine_multiple_dataset
 
 if __name__ == '__main__':
-    dataset_path = os.path.join(SCENARIONET_DATASET_PATH, "nuscenes_no_mapping_test")
+    dataset_paths = [os.path.join(SCENARIONET_DATASET_PATH, "nuscenes")]
+    dataset_paths.append(os.path.join(SCENARIONET_DATASET_PATH, "nuplan"))
+    dataset_paths.append(os.path.join(SCENARIONET_DATASET_PATH, "waymo"))
+    dataset_paths.append(os.path.join(SCENARIONET_DATASET_PATH, "nuscenes"))
+
+    combine_path = os.path.join(SCENARIONET_DATASET_PATH, "combined_dataset")
+    combine_multiple_dataset(combine_path, *dataset_paths, force_overwrite=True, try_generate_missing_file=True)
 
     env = ScenarioEnv(
         {
@@ -16,7 +24,7 @@ if __name__ == '__main__':
             "show_interface": True,
             "show_logo": False,
             "show_fps": False,
-            "num_scenarios": 10,
+            "num_scenarios": get_number_of_scenarios(combine_path),
             "horizon": 1000,
             "no_static_vehicles": True,
             "vehicle_config": dict(
@@ -26,7 +34,7 @@ if __name__ == '__main__':
                 lane_line_detector=dict(num_lasers=12, distance=50),
                 side_detector=dict(num_lasers=160, distance=50)
             ),
-            "data_directory": dataset_path,
+            "data_directory": combine_path,
         }
     )
     success = []
diff --git a/scenarionet/tests/generate_test_dataset.py b/scenarionet/tests/generate_test_dataset.py
index a12dc14..5624e8d 100644
--- a/scenarionet/tests/generate_test_dataset.py
+++ b/scenarionet/tests/generate_test_dataset.py
@@ -9,9 +9,9 @@ from scenarionet.converter.nuscenes.utils import convert_nuscenes_scenario, get_
 from scenarionet.converter.utils import write_to_directory
 
 if __name__ == "__main__":
-    # raise ValueError("Avoid generating ata")
+    raise ValueError("Avoid overwriting existing ata")
     dataset_name = "nuscenes"
-    output_path = os.path.join(SCENARIONET_PACKAGE_PATH, "test", "test_dataset", dataset_name)
+    output_path = os.path.join(SCENARIONET_PACKAGE_PATH, "tests", "test_dataset", dataset_name)
     version = 'v1.0-mini'
     force_overwrite = True
 
diff --git a/scenarionet/tests/test_combine_dataset.py b/scenarionet/tests/test_combine_dataset.py
index e1419d7..36bfc05 100644
--- a/scenarionet/tests/test_combine_dataset.py
+++ b/scenarionet/tests/test_combine_dataset.py
@@ -1,20 +1,17 @@
 import os
 import os.path
 
-import tqdm
-from metadrive.envs.scenario_env import ScenarioEnv
-from metadrive.policy.replay_policy import ReplayEgoCarPolicy
-
 from scenarionet import SCENARIONET_PACKAGE_PATH
 from scenarionet.builder.utils import combine_multiple_dataset, read_dataset_summary, read_scenario
+from scenarionet.verifier.utils import verify_loading_into_metadrive
 
 
 def test_combine_multiple_dataset():
     dataset_name = "nuscenes"
-    original_dataset_path = os.path.join(SCENARIONET_PACKAGE_PATH, "test", "test_dataset", dataset_name)
+    original_dataset_path = os.path.join(SCENARIONET_PACKAGE_PATH, "tests", "test_dataset", dataset_name)
     dataset_paths = [original_dataset_path + "_{}".format(i) for i in range(5)]
 
-    output_path = os.path.join(SCENARIONET_PACKAGE_PATH, "test", "combine")
+    output_path = os.path.join(SCENARIONET_PACKAGE_PATH, "tests", "combine")
     combine_multiple_dataset(output_path,
                              *dataset_paths,
                              force_overwrite=True,
@@ -24,16 +21,7 @@ def test_combine_multiple_dataset():
         summary, sorted_scenarios, mapping = read_dataset_summary(dataset_path)
         for scenario_file in sorted_scenarios:
             read_scenario(os.path.join(dataset_path, mapping[scenario_file], scenario_file))
-
-    env = ScenarioEnv({"agent_policy": ReplayEgoCarPolicy,
-                       "num_scenarios": 10,
-                       "horizon": 1000,
-                       "data_directory": output_path})
-    try:
-        for i in tqdm.tqdm(range(10), desc="Test env loading"):
-            env.reset(force_seed=i)
-    finally:
-        env.close()
+        verify_loading_into_metadrive(dataset_path)
 
 
 if __name__ == '__main__':
diff --git a/scenarionet/verifier/__init__.py b/scenarionet/verifier/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/scenarionet/verifier/utils.py b/scenarionet/verifier/utils.py
new file mode 100644
index 0000000..c0a6cec
--- /dev/null
+++ b/scenarionet/verifier/utils.py
@@ -0,0 +1,28 @@
+import os
+
+import tqdm
+from metadrive.envs.scenario_env import ScenarioEnv
+from metadrive.policy.replay_policy import ReplayEgoCarPolicy
+from metadrive.scenario.utils import get_number_of_scenarios
+
+
+def verify_loading_into_metadrive(dataset_path):
+    scenario_num = get_number_of_scenarios(dataset_path)
+
+    env = ScenarioEnv(
+        {
+            "agent_policy": ReplayEgoCarPolicy,
+            "num_scenarios": scenario_num,
+            "horizon": 1000,
+            "no_static_vehicles": False,
+            "data_directory": dataset_path,
+        }
+    )
+    try:
+        for i in tqdm.tqdm(range(scenario_num)):
+            env.reset(force_seed=i)
+    except Exception as e:
+        file_name = env.engine.data_manager.summary_lookup[i]
+        file_path = os.path.join(dataset_path, env.engine.data_manager.mapping[file_name], file_name)
+        raise ValueError("Scenario Error, seed: {}, file_path: {}. "
+                         "\n Error message: {}".format(i, file_path, e))