Updating / Modify The Record Of Textbox

I retrieve a record on my database through Page_Load event here's the content of my Code:

hMenuID.Value = Request.QueryString["id"];
//Display information of links on the entries
cnDBConnection.ConnectionString = clsFunction.strConnection;
cnDBConnection.Open();
cmModule.Connection = cnDBConnection;
cmModule.CommandText = "SELECT * FROM modules WHERE id=" + clsFunction.ReplaceString(hMenuID.Value.ToString());
rdModule = cmModule.ExecuteReader();
if (rdModule.HasRows == true)
{
rdModule.Read();
txtModuleLabel.Text = rdModule["name"].ToString();
txtModuleLink.Text = rdModule["link"].ToString();
cboParentID.SelectedValue = rdModule["menuid"].ToString();
}
cmModule.Connection.Close();
rdModule.Close();
cnDBConnection.Close();

So, the data appears on my textboxes and a combo box. I tried to modify the content of my textbox and click on the Update button. Unfortunately, there's no modification that happen. Here's my code in the Update button

Code:
if (Page.IsPostBack)
{
if (Page.IsValid)
{
cnDBConnection.ConnectionString = clsFunction.strConnection;
cnDBConnection.Open();
cmModule.Connection = cnDBConnection;
cmModule.CommandText = "UPDATE modules SET name='" + clsFunction.ReplaceString(txtModuleLabel.Text.Trim()) + "', link='" +
clsFunction.ReplaceString(txtModuleLink.Text.Trim()) + "', menuid=" + cboParentID.SelectedValue +
" WHERE id=" + hMenuID.Value;
cmModule.ExecuteNonQuery();
cmModule.Connection.Close();
cnDBConnection.Close();
}
}