In order for your sample library to properly function in Kontakt Player, it's important that all the components of your library folder are in place. How your library looks will depend on which version you're using. How to tell which version of VDL you're using.

Version 2.5.6

This is the root level of what the VDL library folder should look like when using library v2.5.6.

Version 2.5.5 or earlier

Below are two screenshots of the Virtual Drumline 2.5 (version 2.5.5) library folder.

The only difference between the two examples is the presence of .nkc files. These are created by Kontakt once you've started using the library. The other files are of primary importance and if they aren't all present, your library will not properly function.