I'm clueless, I've tried everything and its just not working. I've been masking for years but this new cs4 got me good. Anyone?

Make sure you are painting with white or black at 100% opacity on the mask. Check that your layer opacity is 100%. Check your layer blend mode to make sure that it will have a visible effect. Delete the layer and start over. Use the Mask tool/tab to make your mask adjustments are OK ... ie layer density is OK.

If none of these work, tell us more about what you are doing.

ive done everything, all my settings have been triple checked. just tried again this morning and notta. Its like my brush is turned off or something. i tried 16 then 8 bit tif and psd, assigned 3 different color profiles and nothing. Reset the brushes and all. I honestly am baffled on this one.

yeah my brushes arent working, just tried to paint a new white document and nothing. off to google land.

I figured it out, by default the brushes are set to "pen pressure" even tho I have a wacom and pen I was on a mouse. Oh my!