while runing the script in vugen getting Error -26631: HTTP Status-Code=400 (Bad Request)

I am facing same issue, providing the details here, please help me out.

lr_start_transaction(”Fish_PID”); web_url(”FI-SW-01”, ”URL=https://petstore.octoperf.com/actions/Catalog.action?viewProduct=&productId={product_id}”, ”TargetFrame=”, ”Resource=0”, ”RecContentType=text/html”, ”Referer=https://petstore.octoperf.com/actions/Catalog.action?viewCategory=&categoryId=FISH”, ”Snapshot=t6.inf”, ”Mode=HTML”, LAST); lr_end_transaction(”Fish_PID”,LR_AUTO); lr_think_time(18); IN REPLAY Action.c(112): Warning: The string ’product_id’ with parameter delimiters is not a parameter. Action.c(112): Error -26631: HTTP Status-Code=400 (Bad Request) for ”https://petstore.octoperf.com/actions/Catalog.action?viewProduct=&productId={product_id}” [MsgId: MERR-26631] Action.c(112): web_url(”FI-SW-01”) highest severity level was ”ERROR”, 2133 body bytes, 213 header bytes [MsgId: MMSG-26388] Action.c(112): Notify: Transaction ”Fish_PID” ended with a ”Fail” status (Duration: 0.2811 Wasted Time: 0.0084). Action.c(112): Notify: Transaction ”Fish_PID” has 1 error message(s). Action.c(112): Notify: The 1st error message associated with transaction ”Fish_PID” is ”Error -26631: HTTP Status-Code=400 (Bad Request) for ”https://petstore.octoperf.com/actions/Catalog.action?viewProduct=&productId={product_id}”” Ending action Action.