diff --git a/package/src/pyaslreport/main.py b/package/src/pyaslreport/main.py
index 553e7e5e..ee3fbd1a 100644
--- a/package/src/pyaslreport/main.py
+++ b/package/src/pyaslreport/main.py
@@ -30,10 +30,7 @@ def get_bids_metadata(data):
     dicom_dir = data.get("dicom_dir")
     dicom_header = get_dicom_header(dicom_dir)
     sequence = get_sequence(modality, dicom_header)
-    
-    if sequence is None:
-        raise ValueError(f"No matching sequence found for modality '{modality}' with the provided DICOM header")
-    
+
     return sequence.extract_bids_metadata()
 
 
diff --git a/package/src/pyaslreport/tests/test_package.py b/package/src/pyaslreport/tests/test_package.py
index fda43d33..223b89a3 100644
--- a/package/src/pyaslreport/tests/test_package.py
+++ b/package/src/pyaslreport/tests/test_package.py
@@ -1,6 +1,6 @@
 import pytest
 from unittest.mock import patch, MagicMock
-from .main import get_bids_metadata
+from pyaslreport.main import get_bids_metadata
 
 # filepath: /home/ibrahim/MyPc/Projects/GSoC/ASL-Parameter-Generator/package/src/pyaslreport/test_main.py
 
@@ -24,15 +24,16 @@ def test_get_bids_metadata_no_sequence():
     data = {"modality": "asl", "dicom_dir": "/fake/dir"}
     fake_header = MagicMock()
     with patch("pyaslreport.main.get_dicom_header", return_value=fake_header), \
-         patch("pyaslreport.main.get_sequence", return_value=None):
+         patch("pyaslreport.main.get_sequence", side_effect=ValueError("No ASL sequence class found that matches the DICOM header")):
         with pytest.raises(ValueError) as exc:
             get_bids_metadata(data)
-        assert "No matching sequence found" in str(exc.value)
+        assert "No ASL sequence class found" in str(exc.value)
 
 def test_get_bids_metadata_invalid_modality():
     data = {"modality": None, "dicom_dir": "/fake/dir"}
     fake_header = MagicMock()
     with patch("pyaslreport.main.get_dicom_header", return_value=fake_header), \
-         patch("pyaslreport.main.get_sequence", return_value=None):
-        with pytest.raises(ValueError):
-            get_bids_metadata(data)
\ No newline at end of file
+         patch("pyaslreport.main.get_sequence", side_effect=ValueError("Unsupported modality: None")):
+        with pytest.raises(ValueError) as exc:
+            get_bids_metadata(data)
+        assert "Unsupported modality" in str(exc.value)
\ No newline at end of file