ListDictionary help

I have a ListDictionary. Inside is a byte() key and a ListDictionary value. I have another byte array, it has the exact same length, values, and System.Type of the ListDictionary key. Whenever I try this...

VB Code:

' gotHash is a byte array that is the same as the mainDictionary's only key.
 
Dim nestedDictionary as ListDictionary
nestedDictionary = CType(mainDictionary(gotHash), Byte())

after that step, still no nestedDictionary. I know it's there, I can see it, but I can't use another byte() object to open it up. Why?

If I use the exact same instance of the byte array I used as a key, I can open it up. If I use another byte array with the same values, I can't. Anyone know why that is?