Unfortunately, I wasn't able to download your PSD file successfully. Here are a few ideas:
- You can save GIFs directly from both Photoshop and Illustrator, without the need for Fireworks (if that helps).
- Instead of a GIF, you could try PNG-8, a very similar indexed color format.
- I found that if I had white text selected on the canvas when I opened Image Preview, and then played around with the Matte color (changing it from None to White), I could accidentally get the text to disappear. Somehow, my actions were setting the text's fill to None within the main interface.
- I'd suggest converting your text to outlines before exporting, to see if this fixes the problem. However, it sounds like you're trying a variety of techniques, including flattening to a bitmap, so this may not help.
If the GIF palette is showing you no white or lighter colors, first double-check the file itself: Is the white text still visible? If it is, then maybe try adding the color manually into the GIF palette using the "Add color" button. Or you could try saving a palette from one of the GIFs and loading into the GIF that's giving you problems (there's a fly-out menu for this just above the Format dropdown menu).