I've recorded a HTTP Protocol script on filling a form for driving license in a government web site with a captcha image at the bottom of the form. When i replay the script with different different parameters of mandatory field, does it really insert the raw data into the server on each iteration?. And it doesn't throw an error because the captcha gets changed each time the page gets refreshed.
There may be multiple reasons. If there is any error in application, generally it will be routed to an error page for which actually the server returns http-200 response. This is what LR looks and treat it as valid response and no errors.