ASP.net form getting JS error
<p>I have an ASP.NET form (C#) but which I click this button that should execute a JS method I get the error "Microsoft JScript runtime error: 'document.getElementById(...)' is null or not an object"</p>

<p>This is odd because it should work:</p>

<pre><code>                &lt;asp:LinkButton ID="btnDriverPopulate" runat="server" Text="" Height="55px" Width="172px" CssClass="btnMTO" 
                    OnClientClick="readLicense()" ToolTip="Check Driver" /&gt; 
</code></pre>

<p>textbox code here</p>

<pre><code> &lt;asp:TextBox ID="DriverLast" runat="server" Width="180px" Text='&lt;%# Eval("Last") %&gt;' ToolTip="Enter driver last name"&gt;&lt;/asp:TextBox&gt;
                                    &lt;cc:TextBoxValidator ID="valDriverLast" runat="server" AllowBlank="false" Display="dynamic" ControlToValidate="DriverLast" ValidationGroup="ValGrpDriver"
                                        CorrectFormat="Please enter in alphanumeric characters only." FieldName="Last Name" RegString="^[a-zA-Z0-9\s.,\-']+$" /&gt;
</code></pre>

<p>JS function readLicense that SHOULD set the textbox's value to "hi"</p>

<pre><code>document.getElementById("DriverLast").value = "hi";
</code></pre>
