C# - Retrieve A TextBox From DetailsView?

I have a DetailsView Control, inside as a template a TextBox. I need to findout the value for a TextBox when Inserting data Event handler-, _ItemInserting. The script does not work.

<asp:TemplateField HeaderText="Profile" SortExpression="ContentAuthor">
<ItemTemplate>
<asp:Label ID="uxContentAuthorDisplayer" runat="server" Text='<%# Bind("ContentAuthor") %>'></asp:Label>
</ItemTemplate>
<InsertItemTemplate>
<asp:TextBox ID="uxContentAuthorInput" runat="server" Text='<%# Bind("ContentAuthor") %>'></asp:TextBox>
</InsertItemTemplate>
</asp:TemplateField>

CODE BEHIND

protected void uxInsertAuthor_ItemInserting(object sender, DetailsViewInsertEventArgs e)
{
//// Find control on page
TextBox myAuthorProfile = (TextBox)uxInsertAuthorInput.FindControl("uxContentAuthorDisplayer");
// Set a default value in Data Base if field has been left empty (DB field NOT NULL)
if (string.IsNullOrEmpty(myAuthorProfile.Text))
{
string myAllert = "Field is NULL";
}
else
{
string myAllet = "Field is NOT NULL";
}
}