Stamp duty for wakaf deed

Dear Sir , we are a Bangalore based Muslim employees association , we owned a 40x 30 sft land in north Bangalore where we were running a Madrasa. since our company a center govt affiliate is on the verge of closure as it is defunct. we made a Wakaf deed on Rs 200-/- stamp paper in favor of our sister concern Educational Trust . and further we got the property registered in Karnataka Board of Wakaf , based on the registration with wakaf board we got the Khatha transferred in the name of the new entity and have been paying the BBMP Tax for the last Two years . However at one of the legal forum we have been questioned the validity of the Wakaf deed and people are accusing us of not paying stamp duty for the transfer of the Title from Association to Trust. Hence this approach to get different views on the subject. Thanks in advance for your expert opinion.