I’m trying to write my first caption plugin and having some difficulties.

I’m setting up a shortcode like so:

function Shortcode_Caption( $atts, $content=null ){

   // DEFAULT ARGUMENTS ARRAY       
   $args=shortcode_atts( array(
    'caption' => 'Caption',
    'link' => 'http://www.link.com'
   ), $atts);

   // ENCLOSED SHORTCODES
   if($content){
      return '<div class="Container-Caption" 
        alt="'. $args['caption'] .'" 
        rel="'. $args['link'] .'">
          '.$content.'</div>';
   };
};  

add_shortcode( 'Caption', 'Shortcode_Caption' );

Some JS picks it up from there. So then when the shortcode is used:

[Caption caption="This is the Text" link="http://www.go_here.com"]some content[/Caption]

The above doesn’t work, because of the spaces in the “caption” attribute. However, removing the spaces works 100%:

[Caption caption="Text" link="http://www.go_here.com"]some content[/Caption]

I’m not sure what I’m doing wrong with this?
Thanks!