Why is the RM024 not transmitting unicast packets when TX API is used?

The RM024 uses the last 4 LSBs of the receiving radio's MAC address when sending packets. The TX API feature in the RM024 allows a customer to dynamically address packets to different clients on-the-fly by appending a header to every transmitted packet which includes the 3 LSBs of the receiving radio's MAC address.  This leaves a discrepancy, the RM024 needs the last 4 LSBs but the TX API command only designates 3 LSBs, where do you enter the 4th LSB?  The 4th LSB comes from the Destination Address field, you must have the following programmed into the Destination Address field: xx xx 67 xx xx xx  Where 'xx' is don't care and the '67' is the 4th LSB that must be programmed into the Destination Address field before TX API can be used to send unicast data.