This is a limitation/bug in TestStudio. Here’s where the customer creates the variable: http://10.225.68.127:8080/prweb/PRServlet/nF-qFK4ha1B9XolnJtsJWpQlh9AKUteKa55vdjEHm_Y%5B*/!STANDARD?pzPostData=1316036933 <input type='hidden' id='pzHarnessID' value='HID1CE396E7F15CF6B5FC350407D4BF1FDD'> Test Studio is looking for values that are wrapped in double-quotes. For whatever reason, the server has decided to wrap its values in single quotes, which leads us to fail to identify this as a source. More information along with the test is provided in the internal description.