hi mathu first check which version ur using MS offiice 2003 or 2007 . i think ur using 2003. that code not working in 2003

but i have using  MS office 2007 thats y its working fine for me .if u use 2007 u can get object library 12.0 then u can add refrence in ur project.

then one more thing ur   server  should installed in office 2007 then its working on web application

thank u