Question........ why .... and how do I fix it so that it loads and I can see it before I render it?
Ignore the leaves.

You can force it to display in preview if you do Render -> Reload Textures.  All that's going on is sometimes (quite often, really) the OpenGL preview forgets how to display things like Blender nodes and other material tricks.  It's just cosmetic if it renders correctly.

 Thanks for that pjz99.... that worked... but... if I was wanting to sell the texture, I couldn't expect anyone to do that every time they wanted to use it..... so is there any way around this? I know I have a couple of things that do this and have never known how to fix it.... so thanks for that, now at least I can do that when I use them.

Sometimes a reload problem like this happens because the filename
in the "old part" of the material structure doesn't agree with the filename
in the nodes.  

It's hard to spot this disagreement from inside Poser; it's best to look at
the CR2 file directly and make sure that all the references to each texture
have the exact same relative file path.

Quote -  Thanks for that pjz99.... that worked... but... if I was wanting to sell the texture, I couldn't expect anyone to do that every time they wanted to use it..... so is there any way around this?

I don't see why you think this is something you're doing wrong, but if it really bugs you, stop using blender nodes and flatten any textures together.  This effect you're seeing js just cosmetic, it doesn't matter if the stuff shows up in preview or not as long as it renders correctly.