David Dean
If your data source is defined to call a web service using the http:// protocol, the retrieval will probably fail if you access the published form template via the https:// protocol, because this is seen as being on a different domain. If your form template will be accessed via https, then your web service should also be accessed via https. If this is not possible, then in addition to using Full Trust on your form template you will need to use Central Administration to enable the web service proxy for InfoPath Forms Services.
If your form template needs to be accessible using both http or https, then you may have to modify the data connection URL at runtime using code.
It is possible to use different web service URLs on different sites by using a.udcx file in a Data Connection library to define the web service connection parameters.
- On your MOSS site collection, create a new document library using the Data Connection template.
- In InfoPath, open the Data Connections window, select the data source, and click the Convert... button.
- Save a .udcx file for the web service in the library you created.
- To change the web service URL, download the .udcx file, edit it in Notepad, and upload the .udcx file back to the library.
- Check in and publish the udcx file.
BTW - If you don't see the error message in the Event Viewer on the server, then check the SharePoint log files. By default, these are stored in the folder "C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\LOGS".