If your wind score was not created from a TWS template file the percussion layouts are not included. They are part of the templates only.
Also, make sure you do things in the following order: create staff, assign playback device, load VDL instrument, assign percussion midi map, assign percussion layout. Don't confuse the percussion midi map with the percussion layout. They are 2 different parts of the same puzzle. The mid map is for playback, while the layout is for notation. The only connection between the 2 is the midi note number. It is used for note entry with a midi device and to assign a sound name to the layouts.