I too had this same problem and here is where it starts.
I have a plugin called “Allow multiple accounts”, so what was happening is the User Photo plugin was searching by email and found the wrong account. I was posting as using my user account which has the same email address as the admin account of which does not have a photo.
Here is the fix.
line 103 of user-photo.php change
$userid = (int)$wpdb->get_var("SELECT ID FROM $wpdb->users WHERE user_email = '" . mysql_escape_string($id_or_email) . "'");
TO
$userid = (int)$wpdb->get_var("SELECT ID FROM $wpdb->users WHERE user_login = '" . mysql_escape_string(get_the_author()) . "' and user_email = '" . mysql_escape_string($id_or_email) . "'");
