Rectification u/s 154

Sir, we have received notice u/s 154 for rectification which is also notice for demand. there was a mistake in filling in Tax audit report u/s 44 AB, there was an omission of exp. but in income tax return we have taken that expenses as deduction. now we have received notice u/s 154 which raise a demand by disallowing that particular expenses. How to resolve it..