wp_set_post_terms

I am trying to set terms from meta boxes i have added using add_meta_box(). I’m trying to accomplish something very similar to this post: http://wordpress.stackexchange.com/questions/23917/wp-set-post-terms-example

However I keep running in to the same error when using wp_set_post_terms() and wp_set_object_terms():
Catchable fatal error: Object of class stdClass could not be converted to string in /wp-includes/taxonomy.php on line 2569

I’ve been trying to figure this out for a while. My custom fields look like this after getting all the taxonomies for a particular post:

foreach($taxonomies as $taxonomy) {
      $tax = $taxonomy->name;
      ?>
      <label><?php echo $taxonomy->label['name']; ?></label>

    	<p>
    		<input type="text" name="_ajwiv_vidlib_terms[<?php $tax ?>]" value=""/>
    	</p>
    <?php } ?>

And I am trying to set the terms like this:

if(isset($_POST['_ajwiv_vidlib_terms'])) {
    foreach($_POST['_ajwiv_vidlib_terms'] as $tax => $term) {
      wp_set_post_terms(  $post_id, $terms, $tax );
    }

Any help you could provide would be greatly appreciated.

-AJ