You've got to remember that everyone's built differently and some people are more muscular than others, both of which are going to influence their weight. Plus, it really depends what you're happy with and the weight you feel comfortable at rather than what it says on a chart.
For my height I should weigh (apparently) between 9st 9lb and 12st. Well I know for a fact that if I weighed 9st anything I'd look ridiculous and quite probably ill. I'm aiming for 11st which is what I used to be back in the day and for my build (as I'm not made to be a stick insect) that would be plenty slim enough for me.