if-else statements are not working properly for Appium Java script

I have written a Java code with if-else statements and user would move from 'Screen1' to 'Screen2' through any of 4 alternate routes and I have attached an image for all possible application flows which are decided on the go by of course code written by developer. Just to add tool used is Appium.

    driver.findElement(By.id("----")).click(); //this click will take from  'screen1' to next screen.

    if(driver.findElement(By.id("abc")).isDisplayed())//see if element on 'screen A' is displayed
    {
        //execute a few statements

    }

    else if(driver.findElement(By.id("xyz")).isDisplayed()) //see if element on 'Screen B' is displayed
    {

       //execute a few statements

    if(driver.findElement(By.id("abc")).isDisplayed()) //see if element on 'screen A' is displayed

    {
        // execute
    }

    }
 driver.findElement(By.id("----")); //this is code for 'Screen 2'

What happens is during execution of script, first 'If' is checked and rest all code skipped. I am not able to figure out the issue. Please help.