Uniswap – Fix TransferHelper: TRANSFER_FROM_FAILED Error When Adding Liquidity on Uniswap v2

 function addLiquidity(
    address tokenA,
    address tokenB,
    uint amountADesired,
    uint amountBDesired,
    uint amountAMin,
    uint amountBMin,
    address to,
    uint deadline
) external virtual override ensure(deadline) returns (uint amountA, uint amountB, uint liquidity) {
    (amountA, amountB) = _addLiquidity(tokenA, tokenB, amountADesired, amountBDesired, amountAMin, amountBMin);
    address pair = UniswapV2Library.pairFor(factory, tokenA, tokenB);
    TransferHelper.safeTransferFrom(tokenA, msg.sender, pair, amountA);
    TransferHelper.safeTransferFrom(tokenB, msg.sender, pair, amountB);
    liquidity = IUniswapV2Pair(pair).mint(to);
}

• I have minted 2 ERC Token say Token1 & Token2 and also approved the address of deployed Router v2 contract from Token contracts.
• Also generated the INIT_CODE_HASH in the factory contract and added to the hash value by removing 0X.
• While trying to transact addLiquidity function I am getting an error "TransferHelper: TRANSFER_FROM_FAILED".

I have used the deployed code of Router & Factory contracts from ether scan. I am unable to point out the issue any help will be appreciated.

Thanks in Advance