Doubt in uniswap swap function

#1

I am currently working on a project involving token swapping. swap doesn’t working . Is there any mistake in my code ? I am using Ethereum sepolia test net. but the swap not woring and giving an error that transation failed. Please help if any one knows.

// SPDX-License-Identifier: GPL-2.0-or-later
pragma solidity ^0.8.20;
pragma abicoder v2;

import “https://github.com/Uniswap/v3-periphery/blob/main/contracts/interfaces/ISwapRouter.sol”;

interface IERC20 {
function totalSupply() external view returns (uint256);
function balanceOf(address account) external view returns (uint256);
function transfer(address recipient, uint256 amount) external returns (bool);
function approve(address spender, uint256 amount) external returns (bool);
}

contract SingleSwap {
address public constant routerAddress = 0x3bFA4769FB09eefC5a80d6E87c3B9C650f7Ae48E;
ISwapRouter public immutable swapRouter = ISwapRouter(routerAddress);

address public constant LINK = 0x779877A7B0D9E8603169DdbD7836e478b4624789;
address public constant WETH = 0xfFf9976782d46CC05630D1f6eBAb18b2324d6B14;
address public constant USD = 0x6f14C02Fc1F78322cFd7d707aB90f18baD3B54f5;

IERC20 public WETHToken = IERC20(WETH);

uint24 public constant poolFee = 3000;

constructor() {}

function swapExactInputSingle(uint256 amountIn) external returns (uint256 amountOut) {

    WETHToken.approve(address(swapRouter), amountIn);

    ISwapRouter.ExactInputSingleParams memory params =
        ISwapRouter.ExactInputSingleParams({
            tokenIn: WETH,
            tokenOut: USD,
            fee: poolFee,
            recipient: address(this),
            deadline: block.timestamp,
            amountIn: amountIn,
            amountOutMinimum: 0,
            sqrtPriceLimitX96: 0
        });

    amountOut = swapRouter.exactInputSingle(params);
}

function swapExactOutputSingle(uint256 amountOut, uint256 amountInMaximum) external returns (uint256 amountIn) {

    WETHToken.approve(address(swapRouter), amountInMaximum);

    ISwapRouter.ExactOutputSingleParams memory params =
        ISwapRouter.ExactOutputSingleParams({
            tokenIn: WETH,
            tokenOut: USD,
            fee: poolFee,
            recipient: address(this),
            deadline: block.timestamp,
            amountOut: amountOut,
            amountInMaximum: amountInMaximum,
            sqrtPriceLimitX96: 0
        });

    amountIn = swapRouter.exactOutputSingle(params);

    if (amountIn < amountInMaximum) {
        WETHToken.approve(address(swapRouter), 0);
        WETHToken.transfer(address(this), amountInMaximum - amountIn);
    }
}

}

please help if you guys know.