If the 2000 is anything like the 740 (which it almost certainly is) the tip is live and the sleeve is ground. The ring connection normally shorts the input when no mic is plugged in but becomes an open circuit when it is plugged in. A balanced mic cable uses the tip and ring for the signal, so your cable is open circuit on the ring connection when plugged in. Only way to fix this is to make an adapteror replace the tip/ring/sleeve plug with a mono plug.

Bryan