The scanner delivered a greyscale file, so perhaps the mode has to be changed to CMYK in PS6. I did this.
And the file came with just a background with no other layer. Perhaps backgrounds can't be coloured? I have tried changing/adding a layer and setting the backround on it as blue. It has no effect on the image, which remains black on white.
Ideally the text would act as a mask over a coloured layer. But a legible result with colour would be fine.