I am having issues with a simple login script I created. I was able to record the script successfully but having issues during playback. The page is not loading well.
Your test case is trying to set text into username field immediately after navigating to URL. Too hasty. Your test case should wait for the page to load on browser completely.
In order to make your test case wait, you should insert a line of WebUI.verifyElementPresent() in order to make sure the username filed is present in the page.
WebUI.navigateToUrl(...)
WebUI.verifyElementPresent(findTestObject(' ... appropriate name of test object input_username ...'), 10)
WebUI.setText()