diff --git a/superxas_bec/bec_widgets/widgets/digital_twin/calculations/calc_varia.py b/superxas_bec/bec_widgets/widgets/digital_twin/calculations/calc_varia.py
index c890a28..6027432 100644
--- a/superxas_bec/bec_widgets/widgets/digital_twin/calculations/calc_varia.py
+++ b/superxas_bec/bec_widgets/widgets/digital_twin/calculations/calc_varia.py
@@ -167,6 +167,8 @@ def cm_reflectivity(cm_stripe: str, cm_pitch: float, energy: float) -> float:
     Returns:
         float: Reflectivity [0-1]
     """
+    if cm_stripe is None:
+        return np.nan
     index = bl.cm.surface.index(cm_stripe)
     rs, _ = bl.cm.material[index].get_amplitude(energy, np.sin(cm_pitch))[0:2]
     refl = abs(rs) ** 2
@@ -186,6 +188,8 @@ def fm_reflectivity(fm_stripe: str, fm_pitch: float, energy: float) -> float:
     Returns:
         float: Reflectivity [0-1]
     """
+    if fm_stripe is None:
+        return np.nan
     if fm_stripe in ("Rh (toroid)", "Pt (toroid)"):
         surface = bl.fm.surfaceToroid
         material = bl.fm.materialToroid