Name "ConfigurationManager" is not declared

I have a vb.net 2005 application and I am trying to use the following line to create my connection object:

<CODE>

Dim connDB As SqlConnection = New SqlConnection(ConfigurationManager.ConnectionStrings("someConnectionString").ToString)

</CODE>

but when i do this I get a "name "configurationManager" is not defined" error.  I am thinking that I need to either add a dll or a reference to my project.

Is this right and how do I do this?  thanks much
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