You need to make sure you have references to the NetCil.dll file and the NetUtil.dll files that are in the Class Libraries folder in the dotNetCil folder of the CTIOS toolkit. You should already have but may need the using(import) statements at the top of each file the allow you to refer to the types without using the entire namespace path. In you project look for a References folder. If you already have these files referred to they may be relatively pathed as it looks like you copied the example code to your own folder. If so just either make a lib folder in your project, copy the files there, removed the old references and add them back by browsing to your new location, or just remove them and add them again refering back to the full path of the old location by browsring there. That should fix your problem.