diff --git a/market_trade/core/Ind_bollingerBands.py b/market_trade/core/Ind_bollingerBands.py
index 53ae802..251177d 100644
--- a/market_trade/core/Ind_bollingerBands.py
+++ b/market_trade/core/Ind_bollingerBands.py
@@ -50,12 +50,12 @@ class BB:
                 'window':self.options['window']
             }
         }
-        ans['BB']=CoreTraidMath.CoreMath(self.base_df,opMA).ans
+        ans['BB']=market_trade.core.CoreTraidMath.CoreMath(self.base_df,opMA).ans
         opSTD={'dataType':'ohcl',
             'action':'findSTD',
             'actionOptions':{'valueType':self.options['valueType'],'window':self.options['window']}
         }
-        ans['STD']=CoreTraidMath.CoreMath(self.base_df,opSTD).ans
+        ans['STD']=market_trade.core.CoreTraidMath.CoreMath(self.base_df,opSTD).ans
         ans['pSTD']=ans['BB']+ans['STD']*self.options['kDev']
         ans['mSTD']=ans['BB']-ans['STD']*self.options['kDev']
         ans['x']=np.array(self.base_df['date'][self.options['window']-1:].to_list())