Web HTTP/HTML Protocol - lr_get_transaction_duration throws error

Hi,

I am trying to use this function in simple Web HTTP/HTML script but I am getting the same error. could you please help?

    double trans_time, wait_time;
    
    lr_start_transaction("test");
    
    lr_think_time(2);
    
    web_url("..", 
        "URL=....................", 
         ...............
        LAST);
    
    lr_think_time(5);
    
    lr_end_transaction("test", LR_AUTO);

trans_time = lr_get_transaction_duration("test");

Error message in reply log: "Action.c(25): Error: Failed to get duration of transaction "test"."