I bring a model in and sub divide, I fill everything with white, then I create some grunge with alpha using black (it’s not much but you can definitely see it!), I make my map size 4096 and then Create Texture From Polypaint, my model fills completely with white and the new texture map covers up my grunge…if I turn off the texture map then you can see my grunge again.
What step am I missing??
You can read this post and maybe find your solution >> http://www.zbrushcentral.com/showthread.php?179296-Question-about-textures&p=1031935&viewfull=1#post1031935
I appreciate your help Doug. Maybe if I walk your thru some pics it will be come clearer for you in helping me.
Here is my uv mapped obj already filled with white and the grunge applied.
I click new from Polypaint and the new texture is created but there is no grunge.
If I turn the Texture off my grunge paint comes back! I’m not sure where this is going wrong??
And now, it is displayed, new from polypaint should work.
It’s not on a separate layer which needs to be ‘baked’?
I’m wondering if the UVs are touching / extending beyond the border edges in that thumbnail, possibly causing the white to wrap around and cover up the grunge. Try scaling the UVs down a bit and seeing if it makes a difference.
You can easily check to see if the UV map is the culprit by going to ‘Tool > Texture Map > Create’ and clicking on ‘New From UV Check’. If there is any red in the resulting texture map then ZBrush doesn’t like your UV map. If there is any red, most likely the cause of that, and the solution for it, would be as Cryrid stated.
I finally figured out what I was doing wrong, so I hope this helps others with the same dense brain as mine. 
I had multiple groups and was hiding the other groupings when I painted…don’t do that. If you need to, mask the other groups but don’t hide them…then paint away. If your groups have overlapping uv’s then hide the offending groups/overlapping uv’s and then Create from PolyPainting and you are good to go.
Moral of the story…paint with all of your groups showing…I am not talking different sub-tools but different groupings.
Thanks all for your help. 