Can you try:
private function setFloorLayerDef(floor:String) : void
{
for (var i:int = 0; i < opLayers.length; i++){
trace(opLayers.label);
if (opLayers.label == "Category Codes" || opLayers.label == "Organizations")
{
trace("set Floor " + opLayers.label);
var layer:Layer = opLayers.layer;
if (layer is ArcGISDynamicMapServiceLayer)
{
ArcGISDynamicMapServiceLayer(layer).layerDefinitions = [null, null, null, null, "Floor = '" + floor + "'", "Floor = '" + floor + "'", null, null, null, null, null, null, null, null,];
}
trace(opLayers.layerDefinitions);
//identifyParams.layerIds = i;
//ViewerContainer.getInstance().mapManager.map.getLayer(opLayers.label).visible = true;
}
}
}