无法在http发布请求C#中发送特殊字符

我正在使登录过程自动化，并且在这样做的过程中，我将获得不同类型的密码，其中包括特殊字符.

I am automating the process of sign in and in the process of doing so, I will get different type of passwords which will include special characters.

我的代码如下，并且我尝试使用UrlEncode()密码，该密码不起作用.如果您在我的代码中发现任何问题，或者我可以通过哪种方式找到答案，请告诉我.我的密码是"aab $#*#％232"和"@#:.; $％^& + -__ h1&":

My code is as below and I have tried to UrlEncode() the password, which didn't work. Please let me know if you find any issues in my code or which way i can find a work out. My passwords are "aab$#*#%232" and "@#:.;$%^&+-_h1&" :

string uriString = "http://" + IP + URI ;    
string postData = "";    
TraceLine("The uri string is " + uriString);    
foreach (string key in values.AllKeys)    
{    
    TraceLine(key + "  " + values[key]);    
    postData += key + "=" + values[key] + "&";}}    
    if (postData.Length > 0) {    
    postData = postData.TrimEnd(postData[postData.Length - 1]);
}    
TraceLine("The postData string is " + postData);    
HttpWebRequest req =(HttpWebRequest)System.Net.WebRequest.Create(uriString);    
req.ContentType = "application/x-www-form-urlencoded";    
req.KeepAlive = false;    
req.Method = "POST";    
byte[] bytes = System.Text.Encoding.ASCII.GetBytes(postData);     
req.ContentLength=bytes.Length;    
System.IO.Stream os = req.GetRequestStream();    
os.Write(bytes, 0, bytes.Length);    
os.Close();}