Uselessness of div yields

Tried to figure out how to calculate implied volatilities for a complete index surface today. Didn't come out to well...

Since I didn't have discrete dividends for all the constituents for the underlyings, I tried to use a continous dividend yield. That does not work ... of course. From where to where should the div yield span?

Tomorrow it's time for a redefinition and a hunt for a daily update of the index constituents. Perhaps it's possible to back a relevant and approximate div yield from the futures market. I'll try that as well.