Src link and equals sign dissapearing
===

I am dynamically grabbing image links from a database and inserting them into image tags.  This php code checks if there is a link or not.  If there is a link, that link is inserted into the img code.  If there is no link, a generic "image coming soon" picture is used in its place.

    echo '<tr>
                	<td width="80" height="46">
    				<a href="displayitem.php?item_id='.$top_product_id.'">';
    				if (!is_null($top_link) || $top_link == "")
    				{
    					echo'<img src = "'.$top_link.'" alt="" width="64" height="63" />';
    					//echo $top_link;
    				}
    				else
    				{
    					echo'<img src = "imagen/imagecomingsoon.png" alt="" width="30%" height="40%" />';}
    				echo'</td><td width="108"><a href="displayitem.php?item_id='.$top_product_id.'">'.$final_name.'</a>';
    				echo'</td>
              		</tr>';
				

I have a strange bug that in the event there is no image to link, instead of using the generic image, I get a blank.  When I inspect the blank box, I see that the img tag is not generating properly.  There are no quotes, or even an equals sign after the src designation.  It looks like this.

    <img src alt="" width="64" height="63">

Whey would the entire equals sign dissapear along with the quotes and link in the event I want to use a generic image?