The console is supposed to throw exception if I enter a negative number but it is not working. Am I missing something here?

public decimal CurrentBalance = 1000.00m;
public decimal WithdrawCurrentAmount { get; set; }

public decimal MakeWithdraw()
{
    Console.WriteLine("How much would you like to withdraw from your Current account?", WithdrawCurrentAmount);

    if (WithdrawCurrentAmount < 0) 
    {
        throw new Exception("You cannot withdraw a negative amount" );               
    }

    WithdrawCurrentAmount = Convert.ToDecimal(Console.ReadLine());

    CurrentBalance = CurrentBalance - WithdrawCurrentAmount;
    Console.WriteLine("\nAvailable Current Balance is now: {0}", CurrentBalance);
    return CurrentBalance;     
}