Hra deduction u/s 10

Assessee is working in Mumbai and receives HRA from his employer. He owned a residence house in Mumbai which he is showing has SOP but not residing there (claim Deduction for Hsg loan interest). He stays in rented house in Mumbai and pays the rent for the same. Whether he is eligible to claim HRA Exemption. Employer is denying, even after giving requisites proof like rent agreement, rent receipt etc Kindly guide