diff --git a/backend/app/engine/engine.py b/backend/app/engine/engine.py
index 469a68a..379275e 100644
--- a/backend/app/engine/engine.py
+++ b/backend/app/engine/engine.py
@@ -39,7 +39,8 @@ def makeDescriptionByEngine(sql_database:SQLDatabase):
     return table_schema_objs
 
 def get_Retriever(index,**kwargs):
-    bEnableHybrid = True if os.getenv("HYBRID_ENABLED",False) == True else False
+    strEnableHybrid = os.getenv("HYBRID_ENABLED",'False')
+    bEnableHybrid = True if strEnableHybrid is not None and strEnableHybrid.title() == 'True' else False
     if bEnableHybrid:
         alpha = float(os.getenv("HYBRID_ALPHA", "0.5"))
         retriever = HybridRetriever(index,alpha = alpha,**kwargs)
diff --git a/backend/app/engine/retriever/HybridRetriever.py b/backend/app/engine/retriever/HybridRetriever.py
index b3e9dfb..4bf0b8d 100644
--- a/backend/app/engine/retriever/HybridRetriever.py
+++ b/backend/app/engine/retriever/HybridRetriever.py
@@ -4,7 +4,7 @@ from typing import Optional, Any, Dict, List
 from llama_index.core.base.base_retriever import BaseRetriever
 from llama_index.core.schema import NodeWithScore, QueryBundle
 
-from app.engine.retriever import CHBM25Retriever
+from app.engine.retriever.CHBM25Retriever import CHBM25Retriever
 
 
 class HybridRetriever(BaseRetriever):