selenium webdriver method findElement give Unable to locate element: - selenium

Question

I'm new in testing with selenium (IDE and WebDriver) and Junit i'm facing this problem:
First , i'v learnt how to use selenium IDE with firefox plugin
I create a maven project in Eclipse
Then i used selenium IDE to export the code as java/junit4/webDriver
In eclipse i create a class with code crated by selenium IDE :
public class PB01_TTT {
private WebDriver driver;
private String baseUrl;
private boolean acceptNextAlert = true;
private StringBuffer verificationErrors = new StringBuffer();
WebElement element;
#Before()
public void setUp() throws Exception {
driver = new FirefoxDriver();
baseUrl = "https://w8a.prv:9431";
driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS);
}
#Test
public void testPBO1TTT() throws Exception {
driver.get(baseUrl + "/ProcessPortal/login.jsp");
driver.findElement(By.id("username")).clear();
driver.findElement(By.id("username")).sendKeys("user");
driver.findElement(By.id("password")).clear();
driver.findElement(By.id("password")).sendKeys("password");
driver.findElement(By.cssSelector("span.submit-text")).click();
WebDriverWait wait = new WebDriverWait(driver, 15);
String columnToDisplayXpath = "//html/body/div[2]/div/div/div[1]/div/div/div[2]/div[3]/div/div[1]/div[2]/div[2]/div/div[2]/div[1]/div/div[2]/a";
wait.until(ExpectedConditions.visibilityOfElementLocated(By.xpath(columnToDisplayXpath)));
element = driver.findElement(By.xpath(columnToDisplayXpath));
Assert.assertNotNull(element);
Now when i run my test as junit test all code works until the method --> driver.findElement . It gives to me this error
org.openqa.selenium.NoSuchElementException: Unable to locate element: {"method":"xpath","selector":"//html/body/div[2]/div/div/div[1]/div/div/div[2]/div[3]/div/div[1]/div[2]/div[2]/div/div[2]/div[1]/div/div[2]/a"}
In debug the By.xpath retrieve the element, i'v tried also the By.cssSelector ,but nothig changed. It's the driver findelement that doesn't work.
Any help will be really appraciated