Check the Command Reference on pages 156+.
MY @ 0xFFFE means the Router isn't joined to your Coordinator.
OP is a read-only indicator of what PAN the Router is joined to, so a value of 0 is basically saying the same thing as the MY of 0xFFFE at this point, i.e. your Router isn't joined.
The link above is to the ZB Product Manual, which has a wealth of information on how to form a ZigBee network, so that should be your next stop.