If Sensory Percussion cannot find a sample in one of your samplers it means that the link to that sample got broken somehow - maybe you moved its folder somewhere else on your computer?... It's okay, we're not here to judge! It's easy to fix.
Just right click on the kit with the broken sample links and select "relink samples," then direct Finder or Explorer to the folder on your computer where your samples live. If you forgot where you put them, or have samples saved all over the place, then you can select your entire hard-drive or a high-level folder, but be prepared: it could take a long time for the computer to search through large number of folders.
You can also repair the sample links for an entire set by selecting "repair sample links" from the file menu.
If the broken sample link is from a preset kit (not one you built using your own or third-party samples), then it means that you just need to download and install the sample pack that it came from here. We try to make our sound packs as independent from one another as possible, but there are some dependencies in a few kits in some of the packs, so it's best to install all the packs!