Query related to cash flow

Why the non cash exp. Is to be added back to Net Profit in cash flow & non cash income deducted to net profit i know that We need to show only Actual Net profit which includes only cash item. Then why we not deducting the non cash exp. in to Net Profit in CFS SUPPOSE, we have a Net profit of Rs. 50,000 Further we find out that There is Rs.4,000 of non cash exp which is forgotten to take in P&L In that case The Net Profit will be (50,000-4,000) = 46,000 My question is why we not do the same in CFS I mean to say that why not deducted non cash exp to net profit in cash flow statement.......??