In Excel the workbook must be open to access its document properties.
The syntax would be something like this using Automation...

Dim strAuthor as String
strAuthor = AppXL.Workbooks("Important").BuiltinDocumentProper ties(3)

However, or also, MS supplies a .dll (Dsofile.dll) that allows one to read
and to edit document properties that are associated with Microsoft
Office files. I've used it and it works, but I have found no need for it.
Find it here...
http://support.microsoft.com/kb/224351/en-us
--
Jim Cone
San Francisco, USA
http://www.realezsites.com/bus/primitivesoftware



"Jamie Oglethorpe"

wrote in message .
I don't have VS 2005 Tools for MS Office, so I am trying to do this the old
fashioned way with automation.
I have created the Excel application, and am trying to set the document
properties, such as Title and Author. To that end I have a reference to
Microsoft.Office.Core and am trying to assign
workbook.BuiltinDocumentProperties to a DocumentProperties object (with the
appropriate casting).
I get this exception:

System.InvalidCastException : Unable to cast COM object of type
'System.__ComObject' to interface type
'Microsoft.Office.Core.DocumentProperties'. This operation failed because the
QueryInterface call on the COM component for the interface with IID
'{2DF8D04D-5BFA-101B-BDE5-00AA0044DE52}' failed due to the following error:
No such interface supported (Exception from HRESULT: 0x80004002
(E_NOINTERFACE)).

Help!