Cannot display custom logo image

I am running WP 3.3.1. I recently installed Business 4.1.6, and I am having trouble getting a logo image to display in the header. Under Theme Options \ Header Settings, when I populate "Insert your logo full url here" with a valid URL, the header displays the 'Your site' text from "Enter a site title". If I blank out the value from "Enter a site title", the header displays nothing. If I change the value of "Do you [sic] to use a custom large image logo rather than domain name text?" to 'no', the header displays my site title in small text to the left of the text 'Your site' (which is not right, either, but not really my concern).

My image file is 500x40px, which is the same size as the logo image from the demo site for this theme (http://themetastic.com/buddypress/, select BuddyPress Business from drop-down at upper-right). I even tried using the URL for that image (http://themetastic.com/buddypress/wp-content/uploads/2010/07/business.png), and no dice. I looked for somewhere in the theme options to specify the logo image size, but found nothing. I tried a variety of other images of different sizes, and none showed.

Please advise. Thank you.