not able to click on button after the pop-up appears in appium

Question

I have used appium 1.6.4 and android version is on 5.1 ,6.1 and 7.0

Below is my code

public boolean navigateToLoginPage(){

    String strng = null;
    newObj = new LogInPage();
    wait = new WebDriverWait(driver,20);
    wait.until(ExpectedConditions.visibilityOf(GetStarted));
    GetStarted.click();
    driver.manage().timeouts().implicitlyWait(5000, TimeUnit.MILLISECONDS);

    if(Country.isDisplayed()){
        Country.click();
        wait.until(ExpectedConditions.visibilityOf(Cancel));
        Cancel.click();
    } 
    driver.manage().timeouts().implicitlyWait(4000, TimeUnit.MILLISECONDS); 
    MobileNumber.sendKeys("91**********");

    Next.click();
    driver.manage().timeouts().implicitlyWait(3000, TimeUnit.MILLISECONDS);
    OK.click();// this is the problem , this sometimes works sometimes not 

//i have used the alert interface but no use

//if(OK.isEnabled()){OK.click();} it returns true and I have also used .isDisplayed but no use

//When Ok button is not clicked but the code in the try block is executed //I have also used the tap functionality but no effect

        try {
            strng =newObj.try1();
        } catch (SQLException e) {
            e.printStackTrace();
        }

    wait.until(ExpectedConditions.visibilityOf(EnterOTP));
    EnterOTP.sendKeys(strng);
    Next.click();
    return true;    
}