Billboarding Sprite Question

I'm replacing the wheels on the tablecart but trying to use deform sprite to get the 2D image of the wheels I'm not understanding. If I write it like this:

models/mapobjects/tablecart1ball
{
    deform sprite
    bumpmap    addnormals(models/mapobjects/lab/labcart_wheel/poppawheely_local.tga, heightmap(models/mapobjects/lab/labcart_wheel/poppawheely_h.tga, 4 ) )
    specularmap    models/mapobjects/lab/labcart_wheel/poppawheely_s.tga
    {
        map    models/mapobjects/lab/labcart_wheel/poppawheely_d.tga
        blend    diffusemap
        alphatest    .9
    }
}

The result is wheels that show up totally black in-game. If there's some limitation to deform sprite, I rewrote it to just:

models/mapobjects/tablecart1ball
{
    deform sprite
    {
        blend            blend
        map            models/mapobjects/lab/labcart_wheel/poppawheely_d.tga        
    }
}

With this, it appears the same brightness no matter what. Does anyone know what is wrong with the first material that causes it to draw black or why the second ignores the light in the room?

Interesting...