Find the control in .aspx

My question is how to find the control in the .aspx?
If I am having a listview, where i want the label to display only if my custom control is not visible, I know that i can do this in the code behind, by using .FindControl("cust"), and giving the condition for visible. But if i want to do this in the .aspx page, is it possible to find the control using those tags, I tried it but it is throwing an error " The name 'cust' does not exist in current context
<asp:Listview ID ="ListView1".........
<ItemTemplate> <tr>
<td><asp:HyperLink ID="hyp" ................./></td>
<td><cust:custom ID="cust".............Visible = "condition"...../></td>
<td><asp:Label ID ="lbl" ..............Visible = '<%# !cust.Visible %>'........../></td>
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