My issue with hook_form when creating my own module

so here is my hook form for a module i'm making with a node called conferences, when i call http://mysite.com/node/add/conferences i get the form to display and can add the node. However, after i have submitted the node and go to edit i get the following error:

warning: array_merge_recursive() [function.array-merge-recursive]: Argument #2 is not an array in /path/to/drupal/install/modules/node.module on line 1665.

i've done some searching and as far as i can tell this is the hook that should be called, however it doesn't get called or for some reason no array goes back to the calling function and therefore i get this warning. I'm fairly new to drupal, even newer to writing my own module. I'd appreciate any help, or anyone that might be able to point me in the right direction. If you need to know anything else about my code let me know.

function conferences_form(&$node, &$param)
{
        //Conference name / Journal Name
        $form['title'] = array(
                '#type' => 'textfield',
                '#title' => t('conference/journal name'),
                '#required' => TRUE,
                '#defualt_value' => $node->title,
                '#weight' => -5,
                '#description' => t('Full name of conference or journal')
        );

        //conference short name
        $form['shortname'] = array(
                '#type' => 'textfield',
                '#title' => t('conference/journal shortname'),
                '#required' => TRUE,
                '#defualt_value' => $node->shortname,
                '#weight' => -4,
                '#description' => t('short name of conference or journal/repeat full name if no short name')
        );

        //Description/Comments
        $form['body_filter']['body'] = array(
                '#type' => 'textarea',
                '#title' => t('Description'),
                '#required' => FALSE,
                '#defualt_value' => $node->body,
                '#rows' => 10,
                '#weight' => -3,
                '#description' => t('Short Description of the Conference')
        );
        $form['body_filter']['format'] = filter_form($node->format);

        //year
        $form['year'] = array(
                '#type' => 'textfield',
                '#title' => t('Conference Year'),
                '#required' => FALSE,
                '#defualt_value' => $node->year,
                '#weight' => -2,
                '#description' => t('Format YYYY'),
                '#size' => 4
        );

        //type
        $types = _conferences_types();
        $form['sub_type'] = array(
                '#type' => 'select',
                '#title' => t('Venue Type'),
                '#required' => TRUE,
                '#defualt_value' => $node->sub_type,
                '#options' => $types,
                '#weight' => -1
        );

        //Due Date
        $form['duedate'] = array(
                '#type' => 'textfield',
                '#title' => t('Due Date'),
                '#required' => FALSE,
                '#default_value' => $node->duedate,
                '#weight' => 0,
                '#description' => t('Format dd/mm/yyyy')
        );

        //Conference Date
        $form['conferencedate'] = array(
                '#type' => 'textfield',
                '#title' => t('Conference Date'),
                '#required' => FALSE,
                '#default_value' => $node->conferencedate,
                '#weight' => 1,
                '#description' => t('Format dd/mm/yyyy')
        );

        //Venue
        $form['venue'] = array(
                '#type' => 'textfield',
                '#title' => t('Venue'),
                '#required' => FALSE,
                '#default_value' => $node->venue,
                '#weight' => 2,
                '#description' => t('Enter the venue for the conference/journal')
        );

        //Link
        $form['link'] = array(
                '#type' => 'textfield',
                '#title' => t('Link'),
                '#required' => FALSE,
                '#default_value' => $node->link,
                '#weight' => 3,
                '#description' => t('Link to the conference or journal website')
        );

        //Submission Type
        $submissionType = _conferences_submissionTypes();
        $form['submissiontype'] = array(
                '#type' => 'select',
                '#title' => t('Submission Type'),
                '#required' => TRUE,
                '#defualt_value' => $node->submissiontype,
                '#options' => $submissionType,
                '#weight' => 4
        );

        return $form;
}