Change the settings for the current report so that it can run unattended, and then try to create the subscription or other scheduled operation again. Use the following steps to configure a report to run unattended:
1) Go to the Data Sources properties page of the report that you want to automate.
2) For the Connect Using option, select Credentials stored securely in the report server.
3) Ensure you have a connection type and a valid connection string (ex. data source=cs-sql;initial catalog=QuestReporter).
4) In User Name and Password, type credentials that can be used to access the database. If you are using SQL Server as the data source, the user name must be valid for both logging on to the server and for accessing the database that contains the data for the report.
5)If the user name and password are credentials for a Windows account, select Use as Windows Credentials. If the credentials are for a SQL Server user login, do not select this check box.