Set spacing for brush

HI, I want to set hardness for a brush, but when I use a function to do so, the spacing and diameter is set to 25 automatically. So I use this function to set hardness, spacing and  diameter:

  function setBrushFeatures(Diameter,Hardness,Spacing) { 

  var ref = new ActionReference(); 

  ref.putEnumerated( charIDToTypeID("capp"), charIDToTypeID("Ordn"), charIDToTypeID("Trgt") ); 

  var appDesc = executeActionGet(ref); 

  var toolDesc = appDesc.getObjectValue(stringIDToTypeID('currentToolOptions')); 

  var brushDesc = toolDesc.getObjectValue(stringIDToTypeID('brush')); 

  var desc = new ActionDescriptor(); 

  var ref = new ActionReference(); 

  ref.putEnumerated( charIDToTypeID( "Brsh" ), charIDToTypeID( "Ordn" ), charIDToTypeID( "Trgt" ) ); 

  desc.putReference( charIDToTypeID( "null" ), ref ); 

  var desc1 = new ActionDescriptor(); 

  desc1.putDouble(stringIDToTypeID('diameter'), Diameter); 

  desc1.putDouble(stringIDToTypeID('hardness'), Hardness); 

  desc1.putDouble(stringIDToTypeID('spacing'), Spacing); 

  var desc5 = new ActionDescriptor(); 

  var idnull = charIDToTypeID( "null" ); 

  var ref3 = new ActionReference(); 

  var idBrsh = charIDToTypeID( "Brsh" ); 

  var idOrdn = charIDToTypeID( "Ordn" ); 

  var idTrgt = charIDToTypeID( "Trgt" ); 

  ref3.putEnumerated( idBrsh, idOrdn, idTrgt ); 

  desc5.putReference( idnull, ref3 ); 

   desc5.putObject(charIDToTypeID('T   '), charIDToTypeID('Brsh'), desc1); 

   executeAction(charIDToTypeID('setd'), desc5, DialogModes.NO); 

}

This works but the spacing is not applied, what am I missing?

Cheers

Matthias