Get Details of 500.21 Internal Server Error

I deployed my Sitefinity 4.4 site to a production server, and everything appeared to be working fine. However, when I try to edit a page, through the back-end, I get an error dialog box that says only "IIS 7.5 Detailed Error - 500.21 - Internal Server Error".  I've seen other posts where people getting a 500.21 get more detailed information about a specific configuration issue.  How do I get the additional information, and not just the error dialog box. Also note that the log files in App_Data\Sitefinity\Logs are not being written to.  Is that possibly the root cause? What security setting does the App_data directory need?

Thanks in advance