Redmine

I'm successfully creating Issues from within my solution (version 1.1). Its a bit of a whacky setup, using a plugin designed to support REST functions from within a Filemaker database. The creation of issues is going fine but when I use a POST command to create a time entry I get no response whatsoever. Should I not be using xml to send my data?

https://myAPIkey:user_name@redmineURL.com/time_entries.xml

<time_entry><issue id="8877"/><activity id="9"/><hours>".5"</hours><comments>"comment info here."</comments><spent_on>"2012-02-15"</spent_on></time_entry>