Cannot create data-driven subscription

Hi,

I'm using SQL Server 2005 Developer Edition, which I understand supports Data-driven subscriptions (DDS).

When I try and click on on the DDS button for a report I get the following message:

"Data-driven subscriptions cannot be created because the credentials used to run the report are not stored, the report is using user-defined parameter values, or if a linked report, the link is no longer valid."

1. I have set the data source to use stored credentials.

2. I'm using one simple string parameter

3. Its not a linked report

Any ideas?

regards,

avner