diff --git a/sohstationviewer/view/main_window.py b/sohstationviewer/view/main_window.py
index 4e26efea4e99217b8e625951ab90603c51db7965..bfa52c4e4666131022589881d5bfa9fc594b13ea 100755
--- a/sohstationviewer/view/main_window.py
+++ b/sohstationviewer/view/main_window.py
@@ -546,7 +546,8 @@ class MainWindow(QtWidgets.QMainWindow, UIMainWindow):
                       self.is_plotting_waveform or self.is_plotting_tps)
         if is_working:
             msg = 'Already working'
-            display_tracking_info(self.tracking_info_text_browser, msg, 'info')
+            display_tracking_info(self.tracking_info_text_browser,
+                                  msg, LogType.INFO)
             return
         self.has_problem = False
 
@@ -983,7 +984,7 @@ class MainWindow(QtWidgets.QMainWindow, UIMainWindow):
         """
         display_tracking_info(self.tracking_info_text_browser,
                               'Cleaning up...',
-                              'info')
+                              LogType.INFO)
         if self.data_loader.running:
             self.data_loader.thread.requestInterruption()
             self.data_loader.thread.quit()
diff --git a/sohstationviewer/view/plotting/plotting_widget/multi_threaded_plotting_widget.py b/sohstationviewer/view/plotting/plotting_widget/multi_threaded_plotting_widget.py
index 7e4e0d3abc881a772a494e401860dc9aba221cf7..33ebfb94dcc975d0942115f56dc190dbd402ee2a 100644
--- a/sohstationviewer/view/plotting/plotting_widget/multi_threaded_plotting_widget.py
+++ b/sohstationviewer/view/plotting/plotting_widget/multi_threaded_plotting_widget.py
@@ -1,6 +1,6 @@
 # Define functions to call processor
 
-from typing import Tuple, Union, Dict, List, Optional, Callable
+from typing import Tuple, Union, Dict, List
 
 from PySide2 import QtCore
 
@@ -129,8 +129,8 @@ class MultiThreadedPlottingWidget(PlottingWidget):
         for chan_id in chan_order:
             if need_db_info:
                 chan_db_info = get_chan_plot_info(chan_id,
-                                                self.parent.data_type,
-                                                self.c_mode)
+                                                  self.parent.data_type,
+                                                  self.c_mode)
                 if (chan_db_info['height'] == 0 or
                         chan_db_info['plotType'] == ''):
                     # not draw
@@ -202,7 +202,7 @@ class MultiThreadedPlottingWidget(PlottingWidget):
             self.reset_widget()
             self.is_working = True
             start_msg = f'Plotting {self.name} data...'
-            display_tracking_info(self.tracking_box, start_msg, 'info')
+            display_tracking_info(self.tracking_box, start_msg, LogType.INFO)
             ret = self.init_plot(d_obj, key, start_tm, end_tm,
                                  time_ticks_total)
             if not ret:
@@ -331,7 +331,7 @@ class MultiThreadedPlottingWidget(PlottingWidget):
         all running background threads.
         """
         display_tracking_info(self.tracking_box,
-                              f'{self.name} plot stopped', 'info')
+                              f'{self.name} plot stopped', LogType.INFO)
         self.is_working = False
         self.stopped.emit()
 
@@ -356,7 +356,7 @@ class MultiThreadedPlottingWidget(PlottingWidget):
         if not self.is_working:
             self.is_working = True
             start_msg = 'Zooming in...'
-            display_tracking_info(self.tracking_box, start_msg, 'info')
+            display_tracking_info(self.tracking_box, start_msg, LogType.INFO)
             self.create_plotting_channel_processors(self.plotting_data1)
             self.create_plotting_channel_processors(self.plotting_data2)
             self.process_channel()