Hi Charlotte,
This seems to be a registration issue. Presuming you are using Rasterlink do the following:
– Immediately after creating the special plate (white) select the tab below the special plate tab
– Here you will find options for thinning and thickening.
– You need thinning. Thin the plate by a few pixels. This cuts the white inside the colour plates
– Once complete you can carry on with the layering process
You may need to play about with the number of pixels you thin but from experience you need only have this set to a few pixels.
It also works if you wanted to thicken the plate (ie you wanted to add a white border
Hope this helps.