On Twenty Fourteen Theme not working

Thank you for your plugin, it worked great with my WordPress Pandora Theme, showing one image alone on my excerpt (INDEX.php) and when the reader clicked on READ MORE, it showed a separate image alone (SINGLE.php) in my post.
I recently changed my theme to the new TWENTYFOURTEEN but the thumbnail code doesn’t work in the INDEX.php. I then placed the thumbnail code in the CONTENT.php and the Thumbnail image appears in the excerpt but the Lead Image doesn’t appear by itself in the post when I place its code in the SINGLE.php. What’s happening is that both images are appearing together in the post and not like in Pandora theme which only the Lead Image appeared. I cannot find in this new theme which file to place the Lead Image code so ONLY the Lead Image appears in the post. Below are the 2 codes I used that worked perfect with the Pandora theme. Thank you so much for your help and response, I appreciate it greatly.

Placed in the INDEX.php
<img src=”<?php echo get_post_meta($post->ID, “Thumbnail”, true);?>” />

Placed in the SINGLE.php
<img src=”<?php echo get_post_meta($post->ID, “Lead Image”, true);?>” />

https://wordpress.org/plugins/stumbleupon-digg-thumbnail-maker/