Issue using XBee with Imote2/CC2420 (802.15.4 compliant radio)

I’m trying to communication between an XBee series 2 (XB24-ZB) and an Imote2. The Imote2 is a sensor node with a CC2420 radio (which is 802.15.4 compliant). I’ve successfully performed communication between 2 XBees, then 2 Imote2s, now I’m having an issue with communication between an XBee and Imote2. At this point, I’m using the Imote2 as the transmitter and XBee as the receiver. The XBee simply dumps the message to the console, like a simple XBee chat program. I’ve tried the usual suspects, PAN ID, address and channel.
One possible point of resolution I came across has been the Mac Mode (MM) in the Modem Configuration tab of X-CTU. The Mac Mode enables/disables the MaxStream header which allows communication with other 802.15.4 compliant devices from different vendors. I’ve looked into setting this but it only appears in the older firmware versions. I’ve tried the older versions but they fail to write to the XBee. Also, the ATMM command fails.
Is there anything I’m missing? Has the Mac Mode been removed from the latest firmware versions? If so, does the MaxStream header still exist on the messages? Any help or related information would be greatly appreciated. Thank you

The Xbee S2 will demand various Zigbee messages, which the Imote2 won’t support.

So while the S2 implements 802.15.4, it is like an Ethernet device demanding TCP/IP on top of Ethernet, which prevents a simplier Ethernet-only device from talking to it.

Thank you very much for the reply. I found a Series 1 XBee which allowed this type of communication. The following link was also of great assistance.