Android Appium : Not able enter the text in textbox

//For log in scenario, I just want to enter the userID and password. I tried with different Xpath but still it's not able to identify the box. every-time getting an no such element exception. We are using testNG.

@AndroidFindBy(xpath = "XYZ")
public MobileElement txtUserName;

utils.EnterText(UserNameorMailId,txtUserName);

Different Xpath tried: xyz is placeholder.

 //*[@id='username'] 
//*[@text='Edit Text  ;  Email Address or Username']
//*[@id='layout_usename']//*[@text='Edit Text  ;  Email Address or Username']

Error message:

Method threw 'org.openqa.selenium.NoSuchElementException' exception. Cannot evaluate io.appium.java_client.android.AndroidElement$$EnhancerByCGLIB$$34efbdcd.toString()

I am not sure what else I should try and what exactly the issue is...Help is really appreciated ..