Giving different ContainerControllers different text colors

I'm struggling with setting custom formatting properties on different ContainerControllers assigned to a single TextFlow instance. I can assign different columnCount properties and those display as desired, but other properties such as color seem to be ignored. I have tried this syntax:

myContainerController.color = 0x00ff00;
myContainerController.columnCount = 2;

I have also tried:

var tlf:TextLayoutFormat = new TextLayoutFormat();
tlf.color = 0x00ff00;
tlf.columnCount = 2;
myContainerController.format = tlf;

In both cases, the columnCount is set correctly, but the color is ignored. Is it possible to affect the color of the displayed text? That would seem to be one of the primary advantages of TLF text?

Any help would be appreciated. Thanks!