Fundamental ratio q's

Hi,



I'm using Morningstar research through a Westpac brokerage account to look at company financials/ratios.



With net interest coverage, why would it be negative if earnings are positive and debt/equity is low or even zero?



Also for banks there is no net interest coverage ratio and also no operating margin % listed, what other ratios/figures can I use for banks that are comparable to these?



Would it be net interest margin % and cost income ratio %?



Also for banks instead of debt/equity ratio I am using the capital adequacy ratio, is this appropriate?



And what is the net gearing ratio, how is it different to debt/equity ratio?



Thanks!