How did you put all that graphics into the book module?
Where did you enter the blue rgb value of 0,0,255?
The secret is... it wasn't all done in the book module!
I convereted the photos for the covers to black and white in Lightroom. I then transferred the b&w images into photoshop (as a PSD file using Lightroom's 'edit in...' command) where I added the typography to the top of the image. I enetered the RGB values using the colour choosing icon in photoshop.
After saving, I placed the cover image - now with typography - onto the front cover.
To change the colour of the spine, I first selected the cover. I then scrolled down the right hand panel of the book module until I found the option for 'background colour' (I'm not sure if this is the exact wording as I don't have LR on this PC). If you click the little box, a new window appears containing the colour spectrum. In the bottom right corner of this new window, you can choose to enter a colour as RGB values or hexadecimal.
Defining colours in this precise way, using RGB values, should mean you can accurately control the printed output.
I've done this successfully before, although in that case I used booksmart for the book design and serif pageplus for the cover design. I don't know why it doesn't work with LR4.
What color space was the image in Photoshop when you entered 0,0,255 into the color picker? I assume ProPhoto.
Can you recheck if you set 0.0.255 as page background in the Book module. Did you sample the color with the eye dropper from the photo, by any chance?
The colourspace was ProPhoto (its what I usually work in).
The book module colour was set manually (its too easy to make a mistake with the colour picker). I think I may have set the blue value via the hex code initially and then checked that it was the correct rgb value. I have just noticed that the book module handles colours as percentages, so 0.0.255 = 0%, 0%, 100%.
UPDATE: blurb tech support believe the issue may lie with their Netherlands printing facility but the investigation is ongoing.