DB RTD Troubleshooting

The formula returns #N/A

Use the rtd_LastMessage field to check errors like this:
=RTD("db.rtd",,"sqlexpress","dbo.quotes","symbol","AAPL","rtd_LastMessage")

The data are not refreshed

You can check the refresh interval using the formula like this:
=RTD("db.rtd",,"sqlexpress","dbo.quotes","rtd_RefreshInterval")
and set the interval in seconds like
=RTD("db.rtd",,"sqlexpress","dbo.quotes","rtd_RefreshInterval",15*60)