Problems with PHP if statment

I have been trying to setup a plugin using php. The php file just registers the plugin. The problem is that there are some image files that I want to include in the plugin but the plugin is not picking it up.. I do not get any error messages, its just that when the plugin is installed I do not see the image files, I actully do not know php this is just one file i need to compile for larger project.

<?php

class Plugin_Theme extends DPlugin
{

    public function init()
    {
        DTheme::register($this, $this->getMeta('theme1', 'theme1'));
        DTheme::register($this, $this->getMeta('theme2', 'theme2'));
        DTheme::register($this, $this->getMeta('theme3', 'theme3'));
        DTheme::register($this, $this->getMeta('theme4', 'theme4'));
    }

    private function getMeta($sub_id, $sub_name, $extends = 'default')
    {
        $meta = array (
            'id' => 'maintheme-' . $sub_id,
            'title' => 'maintheme-' . $sub_name,
            'extends' => $extends,
        );
        if ($sub_id != 'theme1') {
            $meta['assets'] = array(
               0 => 'image1.jpg',
               1 => 'image1.jpg',);
        }
        if ($sub_id != 'theme2') {
            $meta['assets'] = array(
                0 =>'image2.jpg',
                1 =>'image2.jpg',);
        }
        if ($sub_id != 'theme3') {
            $meta['assets'] = array(
                0 => 'image3.jpg',
                1 => 'image3.jpg',);
        }
        if ($sub_id != 'theme4') {
            $meta['assets'] = array(
                0 => 'image4.jpg',
                1 => 'image4.jpg',);
        }

        return $meta;
    }
}