Urgent! pls help frnds!

Friends, I am very Confused about presumptive taxation, in 2 problems, am working in excel. 1. The Assessee is doing Money Lending Business.WHETHER MONEY LENDING COMES UNDER THE PURVIEW OF SEC.44AD?  I get Business Loss of 617036.51, as per books. The Only Business income taken for gross receipts is interest received=66393. If i take, business Loss, HE GETS TAX REFUND. IF I APPLY SEC.44AD AND TAKE 8% OF 66393, THE TAX AMOUNT COMES MORE THAN 50000. AM VERY CONFUSED. PLS HELP.. 2.THE SAME QUERY IN 2ND PROBLEM. HE IS NOT A MONEY LENDER. BUT DOES SHARE TRADING AND SPECULATIVE BUSINESS. AM  I SUPPOSE TO TAKE BUSINESS LOSS OR 8% OF ONLY BUSINESS INCOME INTEREST RECEIVED??   PLS PLS REPLY..