Has anybody done scripting of splunk dashboard using loadrunner 11.5 ? Getting authentication issue

Recorded login step in splunk dashboard using http/html protocol using LR 11.5 .While replay the script using VuGen with the same user login credential which has been used during loginn operation I am seeing below authetication issues.

Authentication required,please use web_set_user(),e,g web_set_user("domain\\user","password","host:port");

HTTP status-code=401 (Unauthorized) for "http://<ipaddress:port>/en_US/splunkd/_raw/serviceNS/<username>/search

Please give some pointer on this.I have tried with web_set_user() function with same login credential.I can login application manually using same login credential.

Thanks