SSRS Subscriptions cannot be created because the credentials used to run the report are not stored, or if a linked report, the link is no longer valid.

Have you ever got this message? "Subscriptions cannot be created because the credentials used to run the report are not stored, or if a linked report, the link is no longer valid."

It's simply as it says, just go back to your report and make sure to save the user credintials that runs the report, or go to Datasets under ReportServer.

Also you can refer to this MS 'How to' article.
http://msdn.microsoft.com/en-us/library/ms159736.aspx

Also make sure that your report is not using a User experssion, !userID
Check: http://msdn2.microsoft.com/en-us/library/ms156012.aspx