Test with Selenium 3 fails on Ajax autocomplete

I have a website similar to the facebook name autocomplete. I have to test this function. If I use the sendKeys the text appears in the input, but the ajax suggestions don't show up. If I click manually in the input, the suggestions appears immeadiatly. Can someone help on this?

WebElement searchText_teil = driver.findElement(By.xpath("//input[@class='inputtext textInput']")); searchText_teil.sendKeys("Alix");

wait = new WebDriverWait(driver, 20);
WebElement checkBox_teil_1 = wait.until(ExpectedConditions.visibilityOfElementLocated(By.xpath("//li[@title='Alix ***']")));

searchText_teil.sendKeys(Keys.RETURN);