What is the value of lcFolder at the time of error?

>I have a simple collection named oCalcFolders, which is referenced in the code below.
>
>This is the only place that the collection is touched.
>
>How can I get error 2062," The specified Key already exists" on the next to last line? Doesn't the earlier call to 'GetKey' return a result that indicates whether the key already exists?
>

lcFolder = Trim (loTableInfo.Folder)
>lnIndex = This.oCalcFolders.GetKey (lcFolder)
>If lnIndex # 0
>	lcCalcFolder = This.oCalcFolders (lnIndex)
>Else
>	lcCalcFolder = GetOtherCalcDirectory (Left (lcFolder, At ('\', lcFolder) - 1))
>	This.oCalcFolders.Add (lcCalcFolder, lcFolder)
>Endif