A Microsoft SharePoint Foundation compatible application could not be found

Hi,

I created two Excel Reports and saved them in a SharePoint 2010 folder (with the help of Andrew Lavinsky).

But when I try to edit them in Excel, I get the message:

"Message from webpage: The document could not be opened for editing".

A Microsoft SharePoint Foundation compatible application could not be found to edit the document".

How can I fix this issue?

Thanks for your help.