HI StealthWorks 
The main reason is that the shaders are built for Daz Studio’s shader engine,. and not for Carrara’s.
When the shader is imported, most channels should convert across well, but some settings need to be adjusted,.
It’s usually the Highlight and Shininess channels, but occasionally the bump value or texture map also needs adjusted or added.
Sometimes with Poser shaders, you’ll also get the main “diffuse” texture map, being multiplied with a colour, which is fine for Poser’s shader engine, ..but wrong,. it should only be the texture map.
Carrara comes with a set of V4 and M4 “high-res shaders” which were built for carrara, and you can have a look at those to give you an idea of what shader adjustments should be made.
Once you’ve adjusted the values in all the shaders for a figure,. then the Global shader (multicoloured ball) at the top of the shader list, can be dragged into your My Shaders area of the carrara Browser,.
Then you can apply that to a figure by dragging that “global shader” from the browser, and dropping it onto that Multicoloured ball at the top of the shader list.
Adjusting all the channels in a figure may seem like a lot of work, but since some channels use the same texture maps, you can use the EDIT / remove unused masters / Consolidate duplicate shaders. to minimise the amount of shaders used in the figure.
BUT,. although that’s quick,. it’s not always the best ,. since some channels, like the face and Lips share the same Maps, but have different setting, which you would normally want to keep.
You can Copy and Paste individual shader channel settings from one shader to another, which makes the process a little easier.
Hope it helps 
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