Bse future-option query

I AM JUST SEARCHING THE HISTORICAL DATA AND FOUND THAT IN BSX INDEX FUTURE LAST TRADE PRICE AND SETTLE PRICE ARE TO MUCH DIFFERENT AT SOME DAYS.

I AM PROVIDING THE DETAIL BELOW EXAMPLE OF BSXFEB2013

(IN NIFTY THERE IS ONLY 5-10 POINT MAXIMUM DIFFERENCE )

PLEASE PUT SOME IDEAS ON THAT. CAUSE I WISH TO TRADE IN BSE FO.

SEE THE RED ROWS SPECIALLY.

IF ACCOUNT IS CREDIT-DEBIT IN F&O WITH SETTLE PRICE THAN GOOD DIFFERENCE COME IN CREDIT -DEBIT DUE TO THIS PRICE DIFFERENCE I THINK