Theme function cannot be found Drupal For some reason my theme function is not being found by Drupal.  I swear I have followed everything and spent hours of time trying to make this work to no avail.  Plus with not a single answer in the past 48 hours, Drupal's online support forum is about as much help as a bike with no wheels.  Maybe some of you can figure out what is going wrong with this code.

    function opti_format_results($response) {

    $results = array(

    '#theme' =&gt; 'opti_design'

    );

    if ($response) {

    foreach ($response as $key =&gt; $value) {

    $results['result '.$key] = array(

    '#markup' =&gt; $response[$key]['title'],

    // '#link' =&gt; $response[$key]['link'],

    );

    }

    } else {

    $results[] = opti_nothing_found();

    }

    return $results;

    }


    function Opti_Search_theme() {

      return array(

    'opti_design' =&gt; array(

    'render element' =&gt; 'optisearch'

    )

      );

    }


    function theme_opti_design($variables) {

    $content = $variables['optisearch'];

    var_dump($variables);

    $content = "What is going on??";

    echo "IT HAS THEMED! :D";

    return $content;

    }


The error is quite simple.  "Theme hook opti_design not found."  Can someone please tell me what is wrong.  Everything looks fine.  The hook_theme() function was set properly, and worked in an entirely other module just fine but for whatever reason will not do it's job here.  I feel like it is something simple but I am not seeing it.  Thanks for any and all help.
Your logic is fine, so check these: 


Your module is named 'Opti_Search". If not, Opti_Search_theme() needs to be changed to MODULENAME_theme(), and the caches cleared. This one seems most likely given the error message you received.
You've cleared the caches since implementing hook_theme().
The module is installed and enabled.