.NET script: Check if object exists with If statement?

I'm testing an application where I am supposed to input an organization into a combo box.  Once I click to another field, the system will then apply this logic: If the organization I entered does not exist in the application's database, a popup window will ask if I want to save it.  If the organization was already present in the DB, no popup window displays.

My .NET script behaves correctly when I enter a new organization and click away; the popup opens and the script clicks 'Yes' in that window.  But whenever the organization is already in the system, I get the playback error "XPath expression '@caption='New organization'' is invalid."

Can anybody determine what is wrong with my syntax for the If statement, or suggest a better alternative?  I thought the script would begin at the next line after "End If" if the object doesn't exist. 

Here are the relevant areas of the script:

Imports SilkTest.Ntf.Swt
Public Module Main
    Dim _desktop As Desktop = Agent.Desktop

    Public Sub Main()

    With _desktop.Shell("@caption='Add Record'")

        .ComboBox("[1]").TypeKeys("<OrganizationName>")

        .TextField("[2]").Click

        If .Shell("@caption='New organization'").Exists Then
            With .Shell("@caption='New organization'")
                .SetActive()
                .PushButton("@caption='Yes'").Select()
            End With
        End If

       .PushToolItem("@caption='Save and Close'").Select()

    End With

    End Sub
End Module