diff --git a/View/sediment_calibration_tab.py b/View/sediment_calibration_tab.py
index 970241c..fd5a9a0 100644
--- a/View/sediment_calibration_tab.py
+++ b/View/sediment_calibration_tab.py
@@ -1509,13 +1509,35 @@ class SedimentCalibrationTab(QWidget):
             self.ax_Mfine.plot(stg.M_profile_fine, -stg.range_lin_interp,
                                marker="*", mfc="b", mec="b", ms=8, ls="None")
 
+    def interpolate_data_validity_message_box(self):
+        msgBox = QMessageBox()
+        msgBox.setWindowTitle("Interpolate (step 2)")
+        msgBox.setIconPixmap(
+            QPixmap(
+                self._path_icon("no_approved.png")
+            )
+            .scaledToHeight(32, Qt.SmoothTransformation)
+        )
+        msgBox.setText(
+            "Please select and valid the sample data with"
+            + "click on 'sample plot' button"
+        )
+        msgBox.setStandardButtons(QMessageBox.Ok)
+        msgBox.exec()
+
+
     def interpolate_Mfine_profile(self):
-        data_choice = self.combobox_acoustic_data_choice.currentIndex()
+        # Variable 'stg.sand_sample_target_indice' is set only at
+        # 'plot sample' button click
+        if len(stg.sand_sample_target_indice) == 0:
+            self.interpolate_data_validity_message_box()
+            return
+
+        data_choice = self.combobox_acoustic_data_choice\
+                          .currentIndex()
 
         if stg.depth_cross_section[data_choice].shape != (0,):
-            range_cells = stg.depth_cross_section[data_choice][
-                self.combobox_freq2.currentIndex(), :
-            ]
+            depth_data = stg.depth_cross_section
 
             if stg.time_cross_section[data_choice].shape != (0,):
                 time_data = stg.time_cross_section
@@ -1523,17 +1545,31 @@ class SedimentCalibrationTab(QWidget):
                 time_data = stg.time
 
         else:
-            range_cells=stg.depth[data_choice][
-                self.combobox_freq2.currentIndex(), :
-            ]
+            depth_data = stg.depth
 
             if stg.time_cross_section[data_choice].shape != (0,):
                 time_data = stg.time_cross_sectino
             else:
                 time_data = stg.time
 
-        sample_depth = [-stg.depth_fine[k[1]] for k in stg.fine_sample_profile]
-        M_profile = [stg.Ctot_fine[k[1]] for k in stg.fine_sample_profile]
+        self.interpolate_Mfine_profile_compute(
+            data_choice, depth_data, time_data
+        )
+
+    def interpolate_Mfine_profile_compute(self, data_choice, depth_data, time_data):
+        range_cells=depth_data[data_choice][
+            self.combobox_freq2.currentIndex(), :
+        ]
+
+        sample_depth = [
+            -stg.depth_fine[k[1]]
+            for k in stg.fine_sample_profile
+        ]
+
+        M_profile = [
+            stg.Ctot_fine[k[1]]
+            for k in stg.fine_sample_profile
+        ]
 
         r_bottom = stg.depth_bottom[data_choice][
             np.where(
@@ -1546,7 +1582,7 @@ class SedimentCalibrationTab(QWidget):
                     np.abs(
                         time_data[data_choice][
                             self.combobox_freq2.currentIndex(), :
-                    ]
+                        ]
                         - stg.time_fine[stg.fine_sample_profile[-1][1]])
                 )
             )[0][0]
@@ -1571,7 +1607,9 @@ class SedimentCalibrationTab(QWidget):
 
         stg.range_lin_interp = stg.range_lin_interp
         stg.M_profile_fine = stg.M_profile_fine
-        stg.M_profile_fine = stg.M_profile_fine[:stg.range_lin_interp.shape[0]]
+        stg.M_profile_fine = stg.M_profile_fine[
+            :stg.range_lin_interp.shape[0]
+        ]
 
         self.plot_profile_of_concentration_fine()