Bedrock invoke agent 'overrideSearchType' =HYBRID does not work

I'm using below knowledgeBaseConfigurations to invoke bedrock agent. it cannot find the query. but I test the same query in known based console with search type: HYBRID, I can get query result.

def _invoke_agent(username, sessionId, user_query):
    response = bedrock_agent.invoke_agent(
       agentAliasId=agent_alias_id,
       agentId=agent_id,
       sessionId=sessionId,
       enableTrace=True,
       inputText=user_query,
       sessionState={
           'knowledgeBaseConfigurations' : [
               {
                   'knowledgeBaseId': knowledge_base_id,
                   'retrievalConfiguration': {
                       'vectorSearchConfiguration': {
                            'numberOfResults': 10,
                    **        'overrideSearchType': 'HYBRID'**
                       }
                   }
               } 
           ],
            'promptSessionAttributes': {
                'username': username
            },
            
            'sessionAttributes': {
                'username': username
            }, 
       } 
    )