Error while accessing excel using ADO.net

I am accessing excel sheet through .net 4.0. I am using below connection string.

 

conn = new OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\\Sheet1.xlsx;Extended Properties=Excel 12.0 Xml;HRD=Yes;IMEX=1");

 

Whenever I try to open the connection I get below error.

Could not find installable ISAM.

 

I tried to fix this using the link https://email.accenture.com/owa/redir.aspx?C=3k8eWnK5xkKpN-PRyrOZwOr0VqkLIc8IALyHgHict-IDdbD4tSqAlLhM7W1m-mvDlU-A-LbXFmY.&URL=http%3a%2f%2fsupport.microsoft.com%2fkb%2f209805. However I am not able to find registry key

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Jet\4.0\Engines\Excel

 

I am using Windows 2007 OS.

 

Another thing I noticied is when I tried creating udl I was getting error:The selected DSN contains architectural mismatch between driver and the application. I used OLEDB driver for ODBC and selected excel sheet as data source.

I don't know whether this error is related to above 'could not find installable ISAM' error.

 

Any help would be greatly appreciated