I'm trying to create a function to display either a theme option or custom images based on user input.

So basically, it's a custom meta box. The user selects either a display header image OR they can upload one they want to use.

I've created a custom function to call later on the single page template. This is what I have so far.

//El display image
function el_display(){
    global $post;
    $eldisplay = get_post_meta($post->ID, '_cmb_el_theme', true);
    $elcustomdisplay = get_post_meta($post->ID, '_cmb_custom_image', true);
        
        if(isset($eldisplay)){
            echo '<img src="' . $eldisplay . '" />';
                }elseif(isset($elcustomdisplay)){
                echo '<img src="' . $elcustomdisplay . '" />';
            }else{
                echo '<img src="' . EL_IMG . 'mobile-development.jpg' . '" />';
            }
}

When I call the function later (using el_display(); ), there is no display image showing. I'm a little stuck and have been trying to fix this for hours.

Any help would be much appreciated, thanks!