Selenium Webdriver can't find elements inside of iframes

I'm having some problems trying to run a test with selenium webdriver when an Iframe is present on the code.

There is a single Iframe inside the webpage with that I'm working:

<div class="bwc layout">
    <div class="bwc-frame">
        <iframe id="bwc-frame" class="bwc-frame" src="index.php?module=Campaigns&action=EditView&return_module=Campaigns&return_action=index&bwcFrame=1">
            (...)
        </iframe>
    </div>
</div>

But, when i try to find an element inside of that frame i get this error message:

Exception in thread "main" org.openqa.selenium.NoSuchElementException: Unable to locate element: {"method":"id","selector":"name"}

If i use Selenium IDE i haven't problems finding that element. It happens only with webdriver.

This is my (selenium) code:

WebDriver drive = new FirefoxDriver();
driver.get(myUrl);
WebDriverWait wait = new WebDriverWait(driver, 20);

//Login in my site
wait.until(ExpectedConditions.presenceOfElementLocated(By.name("username")));
driver.findElement(By.name("username")).sendKeys("username");
driver.findElement(By.name("password")).sendKeys("password");
driver.findElement(By.name("login_button")).click();
//end of Login (everything is ok with this part, no Iframes inside)

driver.manage().timeouts().implicitlyWait(20, TimeUnit.SECONDS); //For Web Loading
driver.switchTo().frame(0); //There is a single Iframe 
driver.findElement(By.id("name")); //Webdriver can't find this element

I tried to switch to frame in many different ways:

driver.switchTo().frame(driver.findElement(By.cssSelector("iframe.bwc-frame")));

or

driver.switchTo().frame("bwc-frame");

However I'm getting the same result.

I also tried an explicit wait instead of implicit wait:

wait.until(ExpectedConditions.presenceOfElementLocated(By.cssSelector("iframe.bwc-frame")));

and i get the same result, NoSuchElementException when i try to find the element inside of Iframe.

Please, anyone have any idea why this is failing ? Thanks.