Can someone help me out here?
Thanks.
For some reason they've put the DLC source scripts into subfolders where the CK doesn't see them. You need to move or copy them up a level into the main Data\Scripts\Source folder from the Data\Scripts\Source\Dawnguard folder.
With one of the last updates bethesda changed the creationkit distribution so that all the scripts are packed into a file called 'Scripts.rar'. That is where they should be hiding.
edit: same folder as esp, esm, bsa files or .\Skyrim\Data\
Did you buy Dawnguard or any of the other dlcs?