Creating cookie with a form values makes a null cookie

First of all, i need to create a cookie with a values that are in a form, and a lot of values are in a radio input type, but i ran into a problem with creating it.

Here is the code:

<script>
        function setCookie(name, value, daysToLive) {
    var cookie = name + "=" + encodeURIComponent(value);
    
    if(typeof daysToLive === "number") {

        cookie += "; max-age=" + (daysToLive*24*60*60);
        
        document.cookie = cookie;
    }
}
function getCookie(name) {
    // Split cookie string and get all individual name=value pairs in an array
    var cookieArr = document.cookie.split(";");
    
    // Loop through the array elements
    for(var i = 0; i < cookieArr.length; i++) {
        var cookiePair = cookieArr[i].split("=");
        
        /* Removing whitespace at the beginning of the cookie name
        and compare it with the given string */
        if(name == cookiePair[0].trim()) {
            // Decode the cookie value and return
            return decodeURIComponent(cookiePair[1]);
        }
    }
    
    // Return null if not found
    return null;
}
function checkCookie() {
    // Get cookie using our custom function
    var firstName = getCookie("firstName");
    
    if(firstName != "") {
        alert("Welcome again, " + firstName);
    } else {
        firstName = prompt("Please enter your first name:");
        if(firstName != "" && firstName != null) {
            // Set cookie using our custom function
            setCookie("firstName", firstName, 30);
        }
    }
}
        function createCookie() { 
if (!document.f1.txt1.value) {
alert("Имя не введено");
document.f1.txt1.focus();
}
else { 
    name=document.f1.txt1.value;
    value=document.f1.gender.value+","+document.f1.edu.value+","+document.f1.theme.value;
    setCookie(name,value,4);
    checkCookie();
}
}

i got the code for all the functions from tutorialrepublic.com except the last one, which i made on my own. it should create a cookie from the values which i choose in a form when i click the button here:

<form name="f1">
        <p>Имя: <input type="text" name="txt1">

        <p>Пол: <input type="radio" id="male" name="gender" value="male" checked>
        <label for="male">Мужской</label> <br>
        <input style="margin-left: 215e-2%;" type="radio" id="female" name="gender" value="female">
        <label for="female">Женский</label>

        <p>Образование: <input type="radio" id="elem" name="edu" value="elem" checked>
        <label for="elem">Начальное</label> <br>
        <input style="margin-left: 53E-1%;" type="radio" id="sec" name="edu" value="sec">
        <label for="sec">Среднее</label><br>
        <input style="margin-left: 53E-1%;" type="radio" id="high" name="edu" value="high">
        <label for="high">Высшее</label>

        <p>Цветок: <input type="radio" id="flow1" name="theme" value="flow1" checked>
        <img for="flow1" src="flow1.png" width="200px" height="200px"> 
        <input type="radio" id="flow2" name="theme" value="flow2">
        <img for="flow2" src="flow2.png" width="200px" height="200px">  <br>
        <input style="margin-left: 325E-2%" type="radio" id="flow3" name="theme" value="flow3">
        <img for="flow3" src="flow3.png" width="200px" height="200px"> 
        <input type="radio" id="flow4" name="theme" value="flow4">
        <img for="flow4" src="flow4.jpg" width="200px" height="200px"> 

    </form>
    <button onclick="createCookie()">Create cookie</button>
    <button onclick="checkCookie()">Check cookie</button>

Fortunately, it creates a cookie, but with a null value. i consider that the problem is with the form values types,or with the form itself,but can’t see how i can fix this. i’m new in javascript so this problem can be easy to fix for you. can you help me to find my mistakes?