Quick question on recursive method with strings

[NutmegState]

Hi, I am taking an Intro to Java class right now, and one of our assignments is to write a code that uses a recursive method to compare one string to the reverse of another string (ignoring capitalization). The following code will compile, but will always return the false result, even when it should clearly return true. Can anyone help me find my mistake? Thank you very much!

import java.util.*;

public class CompareString {

	public static void main(String[] args) {
	
	    Scanner console = new Scanner(System.in);
	
	    System.out.print("Please enter a string: ");
	    String firstString = console.nextLine();
	
	    System.out.print("Please enter another string: ");
	    String secondString = console.nextLine();
	
        boolean comparison = isReverse(firstString, secondString);
    
        if (comparison == true) {
            System.out.println("The reverse of one string is the same as the  
            other string, ignoring capitalization.");
        } else {
            System.out.println("The reverse of one string is not the same as the 
            other string.");
	        }
	}
	
	public static boolean isReverse(String firstString, String secondString) {
	
	    String temp = null;
	    
	    if (firstString.length() == 1) {
		    temp = temp + firstString.substring(0, 1);
	        }
	            
	    else {
	                
		    String lastChar = firstString.substring(firstString.length() - 1, 
                    firstString.length());
		
		    String remainingString = firstString.substring(0, 
                    firstString.length() - 1);

		    temp = lastChar + isReverse(remainingString, secondString);
		    }
	    
	    if (temp.equalsIgnoreCase(secondString)) {
	        return true;
	        
	    } else {
	        return false;
	        }
	}
}