I have an updatepanel(named UpdatePanelSignup) inside another updatepanel(named UpdatePanelBusiness)...

UpdatePanelBusiness is set initially to visible=false... 

I also have a dropdownlist(named dropdownlistbusiness) inside UpdatePanelSignup...

I have two choices for the dropdownlist... Yes and No...

I want to make the UpdatePanelBusiness visible when I choose Yes in the dropdownlistbusiness...

Here's the code.. but it creates an exception which is the subject of this post... 

 Dim objdropdown As New DropDownList
        objdropdown = UpdatePanelSignup.FindControl("dropdownlistbusiness")

            If objdropdown.SelectedValue = "Yes" Then
                UpdatePanelSignup.FindControl("updatepanelbusiness").Visible = False
            ElseIf objdropdown.SelectedValue = "No" Then
                UpdatePanelSignup.FindControl("updatepanelbusiness").Visible = True
            End If

 I guess first I'd have to question why you have nested updatepanels. The first panel will refresh without postback when you perform an action inside of the updatepanel (as long as childrenastriggers is set to true). Could you not do a server side div rather than a second update panel?

<!--inside of main update panel-->

<div id="divPanel" runat="server" visible="false">

-- content

</div>

then on the dropdownlists selected item event toggle the div to visible.

Also as far as I know items inside of an update panel can be called just like any other control on the normal page, you don't need to do a updatepanel.findcontrol. 

 thanks! I changed the updatepanel to div and the visible property works...

another question... 

how do I access a dropdownlist in side an updatepanel?

 you'd access it the same way you would if you didn't have it inside of an update panel. Just call it by ID in your codebehind.

 it doesn't appear on the intelisense...

 that happens sometimes to me... try typing it in or copying and pasting the id in and running the code.

 it creates an error

BC30451: Name 'dropdownlistbusiness' is not declared.

 is your updatepanel inside of another container? If so you'll have to do the findcontrol from that container and not from the updatepanel.

i forgot to tell you that inside the updatepanel is a createuserwizard...

the div is inside the createuserwizard...