Small DOS command question

Okay I made a small batch file on my PC that basically just deletes a lot of temporary files and the like. Like temp. internet files, and temp. files that are caused by programs that aren't deleted and the like (Cool Edit Pro does this a lot )

In the file I just use basically "deltree /y C:\folder\*.pk" for instance, and that's all fine and dandy

For whatever reason though, it doesn't delete the files in the folder's subfolders.

Like on my PC, the line is "deltree /y c:\Tony\*.pk", but the files I want are scattered around in the c:\Tony\sounds subfolders, and since I'm constantly re-arranging the folders in there, I'll probably forget to add the different folder names to the file, so instead I'd just like it to delete all the .pk files in the subfolders automatically.

Is there a parameter to add to deltree to make it add to the subfolders as well? 'Cause I thought it just did the folder and everything in it already, but none of the files are getting deleted so I dunno