I'm guessing you've tried selecting your button and then using Inspector's 'fill' button to set it to transparent and that didn't work?
For full transparency, be sure to set the fill pattern to the clear option (next to the solid fill option; may just look white/outline) and then do not again select a color. Choosing a color after sometimes resets it to solid fill.
Also set the borders to none and be sure that all options for embossed/engraved/drop-shadow/etc are set to none.
At that point only the text, if any should appear.( I always include at least a space character as text so the object doesn't disappear from the layout it was created as a text block.) You can create these with either the button or text tools.
So new to this I did not even check the second box to the coloration setting. I thought it would be more editing options, but no idea that they had that in there.