i am getting following error while creating the excel file

> 
> System.UnauthorizedAccessException:
>  Retrieving the COM class factory for
>  component with CLSID
>  {00024500-0000-0000-C000-000000000046}
>  failed due to the following error:
>  80070005 Access is denied. (Exception
>  from HRESULT: 0x80070005
>  (E\_ACCESSDENIED)). at
>  QA.CreateExcel.createDoc() in
>  e:\~~CreateExcel.cs:line
>  33
> 
> 
> 

i am using this code.

```
private Office.Excel.Application app =new Office.Excel.Application();

```

m using fw 4.0 and its a webapplication