Exception in thread "main" FindFailed

public class Google{

    public static void main(String args[]) throws FindFailed{

        System.setProperty("webdriver.chrome.driver", "/Users/venkata.b/Documents/MyProject/rewards-toolbar-chrome-automation/BrowserBinaries/chromedriver");
        WebDriver driver = new ChromeDriver();
        driver.manage().window().maximize();

        driver.get("https://www.google.com");

        Screen s =new Screen();

       Pattern pattern=new Pattern("//Users//venkata.b//Desktop//gmailbtn.png");

       s.wait(pattern, 10);

       s.click("pattern");

Error

Starting ChromeDriver 2.33.506106 (8a06c39c4582fbfbab6966dbb1c38a9173bfb1a2) on port 17858
Only local connections are allowed.
Nov 20, 2017 12:17:45 PM org.openqa.selenium.remote.ProtocolHandshake createSession
INFO: Detected dialect: OSS
Exception in thread "main" FindFailed: //Users//venkata.b//Desktop//gmailbtn.png: (134x60) in S(0)[0,0 1440x900] E:Y, T:3.0
  Line 2759, in file Region.java

 at org.sikuli.script.Region.wait(Region.java:2759)
 at com.toolbar.pages.Google.main(Google.java:24)