diff --git a/src/pygama/flow/__init__.py b/src/pygama/flow/__init__.py
index 384d7603d..fcce73ed6 100644
--- a/src/pygama/flow/__init__.py
+++ b/src/pygama/flow/__init__.py
@@ -4,5 +4,6 @@
 
 from .data_loader import DataLoader
 from .file_db import FileDB
+from .data_group import DataGroup
 
-__all__ = ["DataLoader", "FileDB"]
+__all__ = ["DataLoader", "FileDB", "DataGroup"]
diff --git a/src/pygama/flow/file_db.py b/src/pygama/flow/file_db.py
index 4683737c0..2639b3122 100644
--- a/src/pygama/flow/file_db.py
+++ b/src/pygama/flow/file_db.py
@@ -226,7 +226,7 @@ def scan_files(self, dirs: list[str] = None) -> None:
             scan_dirs = [dirs]
 
         log.info(f"scanning {scan_dirs} with template {template}")
-
+        print(f"scanning {scan_dirs} with template {template}")
         for scan_dir in scan_dirs:
             # some logic to guess where the scan directory is
             if not os.path.isabs(scan_dir):
@@ -240,9 +240,11 @@ def scan_files(self, dirs: list[str] = None) -> None:
                     scan_dir = os.path.join(os.getcwd(), scan_dir)
 
             log.debug(f"scanning {scan_dir}")
+            print(f"scanning {scan_dir}")
 
             for path, _, files in os.walk(scan_dir):
                 log.debug(f"scanning {path}")
+                print(f"scanning {path}")
                 n_files += len(files)
 
                 for f in files:
diff --git a/tests/flow/test_data_loader.py b/tests/flow/test_data_loader.py
index 3c3b857f9..7236fa73a 100644
--- a/tests/flow/test_data_loader.py
+++ b/tests/flow/test_data_loader.py
@@ -84,22 +84,34 @@ def test_no_merge(test_dl):
 
 def test_outputs(test_dl):
     test_dl.set_files("type == 'phy'")
-    test_dl.set_datastreams([1057600, 1059201], "ch")
+    test_dl.set_datastreams([1057600, 1084803], "ch")
     test_dl.set_output(
-        fmt="pd.DataFrame", columns=["timestamp", "channel", "energies", "energy_in_pe"]
+        fmt="pd.DataFrame", columns=["energies", "trapEmax", "is_valid_0vbb", "is_valid_hit"]
     )
     data = test_dl.load()
 
     assert isinstance(data, pd.DataFrame)
-    assert list(data.keys()) == [
+    assert set(data.keys()) == set([
         "hit_table",
         "hit_idx",
         "file",
-        "timestamp",
-        "channel",
+ #       "timestamp",
+ #       "channel",
         "energies",
-        "energy_in_pe",
-    ]
+ #       "energy_in_pe",
+        "trapEmax",
+        "is_valid_0vbb",
+        "is_valid_hit"
+    ])
+    print(data)
+    for id, row in data.iterrows():
+        print()
+        if row.hit_table == 1057600:
+            print( row.is_valid_0vbb == False )
+            print( row.trapEmax < 1e-20 )
+        else:
+            print( (np.array(row.energies) < 1e-20).all() )
+            print( True not in row.is_valid_hit )
 
 
 def test_any_mode(test_dl):