Accessing a CheckBoxField

[dwg1011]

I have a detailview with several fields ending with the CheckBoxField shown
below:

<asp:CheckBoxFi eld DataField="aruE xtraFields"
HeaderText="Ext ra Fields?"
ReadOnly="false "
SortExpression= "aruExtraFields " />
</Fields>
</asp:DetailsView >

Please note the asp control is NOT part of a template.

In the code behind in the AlertRulesDetai l_ItemUpdated, I am trying to
access the value of the field using the code:

Dim CheckBoxName As CheckBox
CheckBoxName =
CType(AlertRule sDetailView.Fin dControl("aruEx traFields"), CheckBox)

Unfortunately, the FindControl does not return anything. I have also tried
declaring the CheckBoxName field as CheckBoxField and changing the type in
the FindControl, but that doesn't work either.

Can somebody please tell me what I am doing wrong.

Thanks,
David