Trapping SelectedValue Exception on dd

[randy.buchholz]

I am trying to trap the following error. I have tried to catch it on page
load and every event on the data source and dd. No luck.
I'm forcing the error by setting the dd.text to an invalid value on page
load which seems to be when the exception is thrown. How can I trap it?
Thanks.

Exception Details: System.Argument OutOfRangeExcep tion: 'DropDownList1' has a
SelectedValue which is invalid because it does not exist in the list of
items.
Parameter name: value

<asp:DropDownLi st ID="DropDownLis t1" runat="server"
DataSourceID="S qlDataSource1" DataTextField=" Certification"
DataValueField= "Certificat ion" Width="200px">

</asp:DropDownLis t>
<asp:Label ID="lbl_Error" runat="server" Text="Label"></asp:Label>

<asp:SqlDataSou rce ID="SqlDataSour ce1" runat="server" ConnectionStrin g="<%$
ConnectionStrin gs:ToteConnecti on %>"

SelectCommand=" SELECT [Certification] FROM [CertTypes]">

</asp:SqlDataSour ce>

protected void Page_Load(objec t sender, EventArgs e)
{
try
{
DropDownList1.T ext = "hello";
}
catch (ArgumentOutOfR angeException ar)
{
lbl_Error.Text = ar.Message;
}

catch (Exception ex)
{
lbl_Error.Text = ex.Message;
}
}
protected void SqlDataSource1_ Event??(object sender, EventArgs e)
{
try
{
DropDownList1.T ext = "hello";
}
catch (ArgumentOutOfR angeException ar)
{
lbl_Error.Text = ar.Message;
}

catch (Exception ex)
{
lbl_Error.Text = ex.Message;
}
}
protected void SqlDataSource1_ Event??(object sender, EventArgs e)
{
try
{
DropDownList1.T ext = "hello";
}
catch (ArgumentOutOfR angeException ar)
{
lbl_Error.Text = ar.Message;
}

catch (Exception ex)
{
lbl_Error.Text = ex.Message;
}
}