I do not know anything about this thumbnail, but your code does the following:
– if the plugin is activated, then it calls the function
– only if the plugin is de-activated, the_excerpt() function is called.
I think you want to do this:
<?php if ( function_exists( 'dp_post_thumbnail' ) ) {
if(!empty(dp_post_thumbnail()){
dp_post_thumbnail();
} else {
the_excerpt();
}
}
?>
This only works if the dp_post_thumbnail() function returns a value. Please check that.
