Cause: You are not authorized to call the Excel component.
1. Enter dcomcnfg.exe in "start"-> "run" to start "Component Service"
2. Double-click "component service"> "computer"> "my computer"> "DCOM configuration"
3. Find "Microsoft Excel application" in "DCOM configuration", right-click it, and click "properties". The "Microsoft Excel application properties" dialog box is displayed.
4. Click the "ID" tab and select "Interactive User"
5. click the "Security" tab, click "Custom" on "Start and activate Permissions", and then click the corresponding "edit" button, in the pop-up "security" dialog box, add a "Network Service" user (note that you must select the computer name) and grant it the "local start" and "Local activation" permissions.
6. still "security" label, click "Custom" on "Access Permissions", and then click "edit ", in the pop-up "security" dialog box, add a "Network Service" user and grant "local access" permission.
Iis7 in window 7: (the ASPNET account of the earlier version of IIS is ASPnet, and iis7 isNETWORK SERVICE)