Only 'echo' if custom fields exist

I’m having trouble creating 2 custom fields. I tried looking at get_post_custom() but I got in way over my head, because it was breaking the code somehow.

What I need is to add a Publication date and the publication name (like a magazine for instance) so it looks like this:

Published: 03/12/2010 in Suchandsuch Magazine

The code I have currently works, but it shows the “Published:” and “in” text even if there’s no custom field added, so I need to figure out how to hide that text if there is no custom fields added.

Here’s my current code.

Functions.php file:

function get_custom_field_value($szKey, $bPrint = false) {
	global $post;
	$szValue = get_post_meta($post->ID, $szKey, true);
	if ( $bPrint == false ) return $szValue; else echo $szValue;
}

In the loop:

<?php if ( function_exists('get_custom_field_value') ){
        echo 'Original Publication: ';
        get_custom_field_value('publication_date', true);
} ?> <?php if ( function_exists('get_custom_field_value') ){
        echo 'in ';
        get_custom_field_value('publication', true);
} ?>

Does anyone know how to hide the echo text if there’s no custom fields there?

Thanks!~