what version of xbee firmware is the X4 running? you can check in the X4 web interface: homepage -> configuration -> xbee network.
You'll want to make sure that waspmote supports either the Zigbee PRO or Zigbee 2006 stacks. You can adjust the X4s setting of this at: homepage -> configuration -> xbee network -> (click on the address of the coordinator) -> advanced settings. ZS = 1 is Zigbee 2006. ZS = 2 is Zigbee PRO stack mode.