Unit Testing Error - The unit test adapter failed to connect to the data source or to read the data

I'm using VSTS 2K8 and I've set up a Unit Test Project. In it, I have a test class with a method that does a simple assertion. I'm using an Excel 2007 spreadsheet as my data source.
My test method looks like this:
        [DataSource("System.Data.Odbc",  
        "Dsn=Excel Files;dbq=|DataDirectory|\\MyTestData.xlsx;defaultdir=C:\\TestData;driverid=1046;maxbuffersize=2048;pagetimeout=5",  
        "Sheet1",  
        DataAccessMethod.Sequential)] 
    [De ...