Do you actually receive the packet?
I'd check the wiring again, and their mapping in the sketch, and again... From Matthijs' documentation:
For example, when a LoRa transmission starts, the DIO0 pin is configured as a TxDone output. When the transmission is complete, the DIO0 pin is made high by the transceiver, which can be detected by the LMIC library.
In LoRa mode the DIO pins are used as follows:
DIO0: TxDone and RxDone