WP_Query par nom de catégorie

Bonjour,j'utilise du codepour afficher les articles dans un curseur sur unepage,et en hautj'ai du codepour lefiltrer à l'aide de WP_Query. Le voici,je ne saispas ce quine vapas:

 <?php
/**
 * Featured Content 2
 *
 */

$args = array(
    'post_type' => 'iv_post_type',
    'category'    => 'commitment',
);
$loop = new WP_Query( $args );      
if ( $loop->have_posts() ) : ?>

    <div id="video-sidebar-right">

        <div class="featured-current-wrapper">

            <div id="featured-content">     

                <?php while ( $loop->have_posts() ) : $loop->the_post(); ?>

                        <div class="featured-post">
                            <?php if(has_post_thumbnail()) :?>
                                <a href="<?php the_permalink(); ?>"><?php the_post_thumbnail( 'bcc-video-medium' ); ?></a>
                                <a href="<?php the_permalink(); ?>"><?php the_title(); ?></a>
                                <?php the_excerpt(); ?> 
                            <?php else :?>

                            <?php endif;?>

                        </div> <!-- .featured-post -->

                        <div class="featured-post-pager">
                            <span id="slider-prev" class="slider-nav">&larr; Next Photo</span>
                            <span id="slider-next" class="slider-nav">&rarr; Previous Photo</span>
                        </div>

                <?php endwhile; ?>


            </div><!-- #featured-content -->
        </div><!-- .featured-current-wrapper -->
    </div><!-- #video-sidebar-right -->

    <div id="video-featured-content">

        <div class="featured-video">
            <div class="videoWrapper">
                <iframe width="640" height="360" src="//www.youtube.com/embed/so_PO0dP3oA" frameborder="0" allowfullscreen></iframe>
            </div>
        </div>

        <?php wp_nav_menu( array( 'theme_location' => 'bcc-video-menu' ) ); ?>

        <p class="video-choose-cat">Choose a category from above to view our different articles.</p>

        <div id="slider-nav">

            <div id="slide-thumbs">

                <?php $slidecount = 1;

                while ( $loop->have_posts() ) : $loop->the_post(); ?>

                    <div class="slide-thumbs-single <?php echo ( $slidecount == -1 ) ? 'last' : ''; ?>">
                        <?php if(has_post_thumbnail()) :?>
                            <?php the_post_thumbnail( 'bcc-video-thumb' ); ?>
                        <?php else :?>

                        <?php endif;?>
                    </div>

                    <?php $slidecount++; ?>

                <?php endwhile; ?>

            </div><!-- .slide-thumbs -->
        </div><!-- #slider-nav -->
    </div><!-- #video-featured-content -->


<?php endif; ?>
 

Hi I am using some code to display posts in a slider on a page, and at the top I have some code to filter it using WP_Query. Here it is, not sure what is wrong:

<?php
/**
 * Featured Content 2
 *
 */

$args = array(
    'post_type' => 'iv_post_type',
    'category'    => 'commitment',
);
$loop = new WP_Query( $args );      
if ( $loop->have_posts() ) : ?>

    <div id="video-sidebar-right">

        <div class="featured-current-wrapper">

            <div id="featured-content">     

                <?php while ( $loop->have_posts() ) : $loop->the_post(); ?>

                        <div class="featured-post">
                            <?php if(has_post_thumbnail()) :?>
                                <a href="<?php the_permalink(); ?>"><?php the_post_thumbnail( 'bcc-video-medium' ); ?></a>
                                <a href="<?php the_permalink(); ?>"><?php the_title(); ?></a>
                                <?php the_excerpt(); ?> 
                            <?php else :?>

                            <?php endif;?>

                        </div> <!-- .featured-post -->

                        <div class="featured-post-pager">
                            <span id="slider-prev" class="slider-nav">&larr; Next Photo</span>
                            <span id="slider-next" class="slider-nav">&rarr; Previous Photo</span>
                        </div>

                <?php endwhile; ?>


            </div><!-- #featured-content -->
        </div><!-- .featured-current-wrapper -->
    </div><!-- #video-sidebar-right -->

    <div id="video-featured-content">

        <div class="featured-video">
            <div class="videoWrapper">
                <iframe width="640" height="360" src="//www.youtube.com/embed/so_PO0dP3oA" frameborder="0" allowfullscreen></iframe>
            </div>
        </div>

        <?php wp_nav_menu( array( 'theme_location' => 'bcc-video-menu' ) ); ?>

        <p class="video-choose-cat">Choose a category from above to view our different articles.</p>

        <div id="slider-nav">

            <div id="slide-thumbs">

                <?php $slidecount = 1;

                while ( $loop->have_posts() ) : $loop->the_post(); ?>

                    <div class="slide-thumbs-single <?php echo ( $slidecount == -1 ) ? 'last' : ''; ?>">
                        <?php if(has_post_thumbnail()) :?>
                            <?php the_post_thumbnail( 'bcc-video-thumb' ); ?>
                        <?php else :?>

                        <?php endif;?>
                    </div>

                    <?php $slidecount++; ?>

                <?php endwhile; ?>

            </div><!-- .slide-thumbs -->
        </div><!-- #slider-nav -->
    </div><!-- #video-featured-content -->


<?php endif; ?>