Why do I get an Object not set to a reference error when trying to insert values into SQL?

Question

In a button click event I have this

protected void btnPassword_Click(object sender, EventArgs e) 
{ 
    string UserID = "Test"; 
    string password = txtPassword.Text; 
    var random = new Random(); 
    Salt = GenerateSalt(); 
    Iterations = random.Next(10000, 100000); 
    Hash = GenerateHash(password, Salt, (int)Iterations); 
    Response.Write(Hash + "<br />" + Salt + "<br />" + Iterations); 
} 

and I am able to see the results.

Why is it that I get an object reference error when trying to put it into a database:

protected void btnPassword_Click(object sender, EventArgs e) 
{ 
    string UserID = "Test"; 
    string password = txtPassword.Text; 
    var random = new Random(); 
    Salt = GenerateSalt(); 
    Iterations = random.Next(10000, 100000); 
    Hash = GenerateHash(password, Salt, (int)Iterations); 

    // The error occurs on the following line
    using (SqlConnection conn2 = new SqlConnection(ConfigurationManager.ConnectionStrings["SiteSqlServer2"].ConnectionString)) 
    { 
        SqlCommand cmd1 = new SqlCommand(@"INSERT INTO [MyTable](UserID,
                                           Hash, Salt, Iterations) 
                VALUES (@UserID, @Hash, @Salt, @Iterations)", conn2); 
        cmd1.CommandType = CommandType.Text; 
        conn2.Open(); 
        cmd1.Parameters.AddWithValue("@UserId", UserID); 
        cmd1.Parameters.AddWithValue("@Hash", Hash); 
        cmd1.Parameters.AddWithValue("@Salt", Salt); 
        cmd1.Parameters.AddWithValue("@Iterations",Convert.ToInt32(Iterations)); 
        cmd1.ExecuteNonQuery(); 
    } 
}

Stack trace:

[NullReferenceException: Object reference not set to an instance of an object.] ashlandapp_bootstrap.Encrypt.btnPassword_Click(Object sender, EventArgs e) in c:\Users\20002143\Documents\Visual Studio 2012\Projects\ashlandapp-bootstrap\ashlandapp-bootstrap\Encrypt.aspx.cs:66 System.Web.UI.WebControls.Button.OnClick(EventArgs e) +9556538 System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +103 System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10 System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13 System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +35 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1724