cc2420 center frequency

hello,i am trying to figure out why my part of my cc2420 evaluation board can receive packet from cc2420 but can't hear any thing from cc2530,i am pretty sure that cc2530 is ok,so iguess it might be radio center frequency or something.i test every board and confirm my guess.The result is that i fixed my board in 26 channel(2.480GHZ),tested
one is 2.47993988.it is indeed a little different and within 1 MHZ,so could you pro give me a answer that 1000HZ or more(within 1MHZ) off fixed center frequency will lead my transceiver to dumb .thanks a lot ! iam looking forward to your reply.