Thanks for the prompt response Matt! See below for my answers and additional comments or questions:
Q. Is the web server Apache or something else?
A. Apache
Q. Are there any security plugins on the site that’s not working?
A. Not that I could tell
Q. Anything interesting in the logs?
A. No
Q. Can you hit the generated URL through a browser?
A1. Client’s WP site goes to “Page Not Found” error page.
A2. My WP site says “ERROR: No direct access allowed. Post something from Ping.fm instead.” Note: My site seems to post tests using PingFM and HootSuite dashboards.
Q. Is there any plugin installed that could be messing with custom post types?
A. Not that I can tell. Client’s site is a Genesis/StudioPress framework for a real estate broker. Any certain plugin types I should look into?
Thanks again for any suggestions!