问FindElement(By.Id)不工作

EN

// Enter the user name and password 
IWebElement username = FF_Browser.FindElement(By.Name("txtUserName"));
username.SendKeys("user1");
IWebElement password = FF_Browser.FindElement(By.Name("txtPassword"));
password.SendKeys("pw1");
// Click the Login button
FF_Browser.FindElement(By.Name("btnLogon")).Click();

try 
{
bool loginResult = FF_Browser.FindElement(By.Id("lblUserName")).Text == "user1";
return loginResult;   
}
catch (NoSuchElementException)
{
return false;
}