using both auto post back and validators
<p>have a pulldown with both AutoPostback set to true and a validator.
When I select an "invalid" value from the pulldown, the validator message
shows briefly, then a postback occurs and the errormessage is gone!
this is my code:</p>

<pre><code>&lt;asp:TextBox ID="SerialFrom_txt" runat="server" BackColor="White" BorderColor="#188F3E"
                            BorderStyle="Solid" BorderWidth="3px" Width="200px" OnTextChanged="SerialFrom_txt_TextChanged"
                            AutoPostBack="true"&gt;&lt;/asp:TextBox&gt;
                        &lt;asp:RegularExpressionValidator ID="SerialFrom_rv" runat="server" ValidationExpression="^[a-zA-Z]{2}[0-9]{7}$"
                            Text="error" ControlToValidate="SerialFrom_txt" /&gt;
</code></pre>

<p>and my behind code for post back is:</p>

<pre><code>protected void SerialFrom_txt_TextChanged(object sender, EventArgs e)
    {

            if (string.Compare(RoleFrom_lbl.Text, SerialFrom_txt.Text) &gt; 0)
            {
                Error_lbl.Text = "Serial From must be greater than " + RoleFrom_lbl.Text + "!";
                SerialFrom_txt.BackColor = System.Drawing.Color.FromName("red");
                SAVE_btn.Enabled = false;
            }

            else
            {
                Error_lbl.Text = "";
                SerialFrom_txt.BackColor = System.Drawing.Color.FromName("white");
                SAVE_btn.Enabled = true;
            }

    }
</code></pre>

<p>so please tell me what should I do?</p>
