Using an if statement to determine post meta

Hello,

I’m developing a theme and I would like the meta information to be one of two things:

1. “Written by [author name] on [published date].”
2. “Last updated by [author name] on [last updated date].”

Here’s the code I’m using:

<?php
    if ( get_the_modified_time() == get_the_time() ) {
	echo 'Written by ' . the_author() . ' on ' . get_the_date() . '.';
    }
    else {
	echo 'Last updated by ' . the_author() . ' on ' . get_the_modified_date() . '.';
    }
?>

For some reason, this code outputs one of two things (depending upon the post):

1. “[author name]Written by [author name] on [published date].”
2. “[author name]Last updated by [author name] on [last updated date].”

You can see it here: http://dev.leavingworkbehind.com/blog/.

What am I doing wrong?

Cheers!

Tom Ewer