Phil, yours is fine. Seriously, you've just got to get the color balance worked out. Its easier said than done. I've had mixed results with a borrowed ST7 a couple of years ago doing mapped colour. Not all objects suit this type of imaging.
Take your time. Image processing can take longer than the actually aquiring the data. You may also want to obtain a copy of Astrodon's colour weight calculation software.
http://www.astrodon.com/oldsite/ColorExposure.html
Note its not free. Its trial and error. Keep it up. You'll get there.