Problem with PHP custom field in WordPress Shortcode

I'm using the echo do_shortcode function to include an events calendar within a WP template. I need to display a custom field within the shortcode area, but can't get it to work. Below is my code. I need the custom field "tickets" to show in the a href="#" section (replacing the #). The post is a custom post type called "event". <?php echo do_shortcode('[eo_events] <div class="date"> <div class="month">%start{M}%</div> <div class="day">%start{j}%</div> </div> <div class="venue"> <h2 style="margin-bottom:-40px!important; padding-bottom:0;">%event_venue%</h2> <br/>%event_venue_address%<br/>%event_venue_country%, %event_venue_postcode% </div> <div class="city"><h2>%event_venue_city%</h2></div> <div class="tickets"> <h2><a href="#" target="_blank">Tickets</a></h2> </div> [/eo_events]'); ?> Please let me know if you can help with this. Thank you.