Comments template Under tab in php file

Hello,

I am using the great UI tab plugin but facing an issue.I am trying to display the post in a tab name content and comments in another tab name Comments, so the content is working perfectly but the comment part having an issue it displaying out of tabs area. Following is the code which I am using in single.php, So I think template is an issue here.
Hope to get some guideline here.

<?php
      echo do_shortcode('[wptabs][wptabtitle]Content[/wptabtitle]
           [wptabcontent]'.get_the_content().'[/wptabcontent]
  	   [wptabtitle]Comments[/wptabtitle
           [wptabcontent]'.comments_template( '', true )
           .'[/wptabcontent] [/wptabs]' );
?>

Thanks

http://wordpress.org/plugins/wp-ui/