Yes it does work with bitmaps and there are several options available to you.
When you select the paint bucket tool look in the Properties Panel there you will find settings that enable you to...
a. Set the type of fill
b. Set the edge type of fill
c. Set the texture and transparency
d. Set the Tolerance
e. Set the option to fill selection
f. Set the opacity and method of applying color
g. Set the option to preserve transparency
So in your case you would use your magic wand tool to select an area, then check the option to "Fill Selection".
If you have a selection but don't check "Fill Selection" then Fireworks will use the Tolerance setting and fill within the selection only the color values that fall within the tolerance settings.
Hope this helps,
Yes you were right, it does work.
The mistake i made is that i had the opacity pointer to zero.
Thanks for the help.
Thank you, mine was also zero