Charitable trust

my trust is reg u/s 12A.which derived income from house property and on which TDs is deducted.but when I feed this income in hp head then this income is become taxable income so I feed this income in total income. then no tax liability is arises whether such income of trust are liable to tax.or will get exemption u/s 12 .I used compu tax software
and now I recd demand on total income