End Google Ads 201810 - BS.net 01 --> Pleas I need help on this code.

onclick on the save button this problem will prevent it from carry out the operation.
on geting to myCommand.ExecuteNonQuery();
it give me this error below.
{"Must declare the scalar variable \"@Telephone_NoParam\"."}

pls help as I dont know what to do because am new to c#

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;

namespace Kay_Nylon
{
public partial class COMPANY_INFO : Form
{
public COMPANY_INFO()
{
SqlConnection myConnection = new SqlConnection("user id=sa;" +
"password=admin123;server=ADEMOLAPC;" +
"Trusted_Connection=yes;" +
"database=Kay_Nylon_Db; " +
"connection timeout=30");
myConnection.Open();
//myConnection.Close();

InitializeComponent();
}

private void COMPANY_INFO_Load(object sender, EventArgs e)
{
}

private void btnSave_Click(object sender, EventArgs e)
{

SqlConnection myConnection = new SqlConnection("user id=sa;" +
"password=admin123;server=ADEMOLAPC;" +
"Trusted_Connection=yes;" +
"database=Kay_Nylon_Db; " +
"connection timeout=30");
myConnection.Open();

//try
//{

SqlCommand myCommand = new SqlCommand("INSERT INTO Company_Info(Company_Id, Company_Name, Company_Address_Line1, Company_Address_Line2, Telephone_No, Fax, Email) " +
"Values(@Company_IdParam, @Company_NameParam, @Company_Address_Line1Param, @Company_Address_Line2Param, @Telephone_NoParam, @FaxParam, @EmailParam)", myConnection);

myCommand.Parameters.AddWithValue("@Company_IdParam", txtCompanyId.Text);
myCommand.Parameters.AddWithValue("@Company_NameParam", txtCompanyName.Text);
myCommand.Parameters.AddWithValue("@Company_Address_Line1Param", txtAddress1.Text);
myCommand.Parameters.AddWithValue("@Company_Address_Line2Param", txtAddress2.Text);
myCommand.Parameters.AddWithValue("@Telephone_NoParam", txtTelephoneNo.Text);
myCommand.Parameters.AddWithValue("@FaxParam", txtFax.Text);
myCommand.Parameters.AddWithValue("@EmailParam", txtEmail.Text);


myCommand.ExecuteNonQuery();
myConnection.Close();
// }
//catch (Exception sql)
// {
// Console.WriteLine(sql.ToString());
// }
}
}
}