Sale pf Property on Agreemt of Transfer

Sir/Madam My son-in-law and daughter bought residential premises in Pune in 2004 by taking Bank Loan from a reputed bankers. Now the entire loan has been paid-up and we have received the bunch of Original Documents from bank as per the list of the documents submitted to bank while taking a loan from the bank. These documents include (1) Builder+Promoter to Party of First Part as Purchaser in 1989. (2) Agreement of Transfer between Party of the First Part as Transferor and Second Part i.e. My Son-in-Law & my daughter as Transferees in 2004. This agreement is the then value of stamp duty paid and duly stamped & registered in SRO’s office, (3) Society’s ownership transfer letter, NOC, Share Certificate in my son-in-law & daughters names, etc. Now, after 10 years, we want to sale this premises. However when our buyers approached their bankers for loan, their banker’s refused to give loan on the ground that Agreement of Transfer of 2004 between First Part & Second Part is not a valid document for loan and Bankers are asking for Sale Deed. Unknowingly in 2004, sale deed was not made between Transferor and my son-in-law. But I am surprised when my son-in-law was granted loan from his bankers in 2004 on Agreement of Transfer, why not current(2015) buyers’ bankers refused to grant loan. If bankers insist for Sale Deed, how can I get sale deed for transaction done in 2004 on Agreement of Transfer, which is stamp-duty paid and registered in SRO’s office