Dan Brown puts together a good tale, as in Deception Point, but the main thesis (like Deception Point) is so outlandish that bringing it to the screen makes it funny, dull, stupid, you name it.
I think DC will one day be remembered in the same category as the Pet Rock.
Many successful literary ventures don't translate on film. F. Scott Fitzgerald, John O'Hara, and William Faulkner all failed as screen writers.