Good to have your company, SNG. Have you tried using the free Calibre Library software (download here: http://www.calibre-ebook.com
As TheDucks says, though, it's often a matter of Garbage-In-Garbage-Out. A badly prepared digital file will not convert well and a file padlocked bty DRM software won't convert at all without first stripping the DRM (morally justified, I feel, but still not legal).
Good luck and best wishes. Neil