Uniswap V2 Tutorial – How to Swap Tokens Back to Ether

I am trying to do the reverse action of what I did in this question:
Basically sell/swap some arbitrary token and receive ether on Uniswap V2 using IUniswapV2Router02.

Here is what I have done:

 contract SellTokens{
    
       IUniswapV2Router02 usi = IUniswapV2Router02(0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D);
          
    function sellDai(uint256 daiQty , address cryptoToken) public payable returns(uint256){

//address cryptoToken = 0x4F96Fe3b7A6Cf9725f59d353F723c1bDb64CA6Aa;//0x00D811B7d33cECCFcb7435F14cCC274a31CE7F5d//multiDaiKovan;

    uint256 ethAmountDerivable = getEstimatedTokenForETH(daiQty , cryptoToken)[0];
 
  uint deadline = now + 300; // using 'now' for convenience, for mainnet pass deadline from frontend!

    usi.swapExactTokensForETH(daiQty , ethAmountDerivable, getPathForTokenToETH(cryptoToken), address(this), deadline);

   return ethAmountDerivable;

}
    
    function getEstimatedTokenForETH(uint daiQty , address crypto) public view returns (uint[] memory) {
        return usi.getAmountsIn(daiQty, getPathForTokenToETH(crypto));
      }
    
     function getPathForTokenToETH(address crypto) private view returns (address[] memory) {
        address[] memory path = new address[](2);
        path[0] = crypto;
        path[1] = usi.WETH();
        
        return path;
      }
    
    }

When I call sellDai from truffle console using:

c.sellDai(web3.utils.toWei('0.02'),'0x4F96Fe3b7A6Cf9725f59d353F723c1bDb64CA6Aa',{value: 3000000000000000})

I get the following output

The status says:
Fail with error 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT'

What could be the issue, please?

EDIT

I changed the getAmountsIn function call to getAmountsOut, and the error changed from INSUFFICIENT_OUTPUT_AMOUNT to TransferHelper: TRANSFER_FROM_FAILED.

EDIT 2

After the admonition to approve the token before transfer, I did this:

function sellDai(uint256 daiQty , address cryptoToken) public payable returns(uint256){

//address cryptoToken = 0x4F96Fe3b7A6Cf9725f59d353F723c1bDb64CA6Aa;//0x00D811B7d33cECCFcb7435F14cCC274a31CE7F5d//multiDaiKovan;

  uint256 ethAmountDerivable = getEstimatedTokenForETH(daiQty , cryptoToken)[0];
  ethAmountDerivable = ethAmountDerivable.mul(10).div(11);// divide by 1.1
 
  uint deadline = now + 300; // using 'now' for convenience, for mainnet pass deadline from frontend!

  IERC20 dai = IERC20(cryptoToken);
  dai.approve(address(this), 0);
  dai.approve(address(this), daiQty);

    usi.swapExactTokensForETH(daiQty , ethAmountDerivable, getPathForTokenToETH(cryptoToken), address(this), deadline);

   return ethAmountDerivable;

}

But it still didnt work. Any ideas please. Here is the transaction

Thanks again