db.execute in flask sqlite3 error:Parse error: no such column

i dont know why the sqllite error :Parse error: no such column my database table is

CREATE TABLE users (
    "id" INTEGER PRIMARY KEY AUTOINCREMENT,
    "username" TEXT(32) NOT NULL,
    "userpass" TEXT(16)
);

Of course, the output of flask says args = 3 and I don't understand where the problem is

@app.route("/singup",methods=['POST','GET'])
def singup():
    if request.method == "GET":
        return render_template("/singup.html")
    else:
        session.clear()
        islogin = False
        username = request.form.get("username")
        password = request.form.get("userpass")
        confirmpassword = request.form.get("conuserpass")
        if not username:
            flash("enter Username", "403")
            return render_template("/singup.html")
        elif not password:
            flash("Enter password", "info")
            return render_template("/singup.html")
        elif not confirmpassword:
            flash("Enter password confirmation", "info")
            return render_template("/singup.html")
        elif confirmpassword != password:
            flash("the password not be same", "info")
            return render_template("/singup.html")
        try:
            new_user = db.execute("INSERT INTO users (userpass,userpass) VALUES(?,?);",[username],[password])
        except:
            flash("user name is exist")
            return render_template("/singup.html")
        session["user_id"]=new_user
        islogin = True
        return redirect("/")