SwapExactTokensForETH On Pancakeswap

[mahanamiri]

Hello, I implemented the following code:

 var privatekey = "...";

        Account account = new Account(privatekey);

        var web3 = new Web3(account, "https://bsc-dataseed1.binance.org:443");


        var routerV2Address = "0x10ED43C718714eb63d5aA57B78B54704E256024E";
        var uniswapV2Router02Service = new UniswapV2Router02Service(web3, routerV2Address);

        var bnb = "0xbb4cdb9cbd36b01bd1cbaebf2de08d9173bc095c";
        var pa = "0x7F11290E06bfeda487A8ce23d86cFD7E8f5e66c8";

 var path = new List<string> { pa, bnb };

        BigInteger amountSCN = 100000000000;

        var serviceSCN = new Nethereum.StandardTokenEIP20.StandardTokenService(web3, pa);

var deadline = DateTimeOffset.Now.AddMinutes(85).ToUnixTimeSeconds();

        var swapTokensForExactTokens = new Nethereum.Uniswap.Contracts.UniswapV2Router02.ContractDefinition.SwapExactTokensForETHFunction
        {
            AmountOutMin = Web3.Convert.ToWei(0),
            Path = path,
            Deadline = deadline,
            To = account.Address,
            AmountIn = amountSCN,
            GasPrice = Web3.Convert.ToWei(20, UnitConversion.EthUnit.Gwei),
            Gas = 100000
        };

var approveReceipt = await serviceSCN.ApproveRequestAndWaitForReceiptAsync("0x10ED43C718714eb63d5aA57B78B54704E256024E", 109828292673427);

var swapReceipt = await uniswapV2Router02Service.SwapExactTokensForETHRequestAndWaitForReceiptAsync(swapTokensForExactTokens);

But my problems are not solved by the following method:

var approveReceipt = await serviceSCN.ApproveRequestAndWaitForReceiptAsync("0x10ED43C718714eb63d5aA57B78B54704E256024E", 109828292673427);

I manually called this method via smart contract:
https://bscscan.com/tx/0x8d985fbbea13e895bb20e00a5607520da4137d026445a6d882dfe4224c365568

And after that I called the next step of the code:

var swapReceipt = await uniswapV2Router02Service.SwapExactTokensForETHRequestAndWaitForReceiptAsync(swapTokensForExactTokens);

Unfortunately, I tried many times and failed every time.

https://bscscan.com/tx/0xaf43bd21b1263c43e4afeb041ee8d9d0a256318396dced6a43fe3c43448176d8