TDS for commercial property co-owned by a senior citizen

I have rented a commercial space in name of my partnership firm since Jan 2007 on a 3 years lease. I have paid 4 months security (refundable ) equalling 64000 /- and the following rental payments:

FY : 2007 - 2008 - Total Rent paid  = 196800

FY : 2008 - 2009 - Total Rent paid  = 216480

FY : 2009 - 2010 - Total Rent to be paid  = 174240 ( from April 2009 till December 2009 only)

The Property owner is a senior citizen and cheques paid are in his name, although the property is owned by him, his wife and childrens jointly. The issue is that he says being a senior citizen he is not liable for TDS. I assume it would have been true if he had no other income and am looking for some help on this here. Actually he owns other properties also and gets good amount of rental income from them as well. Much higher rents than what i am paying.

Can someone guide me as t,o if i am liable for not deducting and depositing of TDS on his behalf. I have not deducted and TDS till now for the rent. Although i do deposit TDS for employees and few contractors on a regular basis. Also, since i have not deducted TDS for the rented premises, how will it be viewed by the Tax Authorities and will they raise any demand on me or on the Property owner . Any help will be highly appreciated.

Thanks

Ronny