Sometimes if you ahve it listed in TWO MLS's the second one won't go through because the address is the same.
However, I have found that regardless of if your company feeds direct to Trulia, you can go to MY Listings and manually add it and/or edit it.. If it's a problem still, contact Trulia for help. They are very responsive.
How does your listing come to Trulia? Through direct feed from you broker? I use Real Bird and they syndicate my listings to Trulia and then I update the listing once its on here. Is the listing coming up when you search the address on Trulia?