successful join but link failed

Hi All

my platform is TM4C129+CC1200,I have done the simple peer-to-peer communication,and now I try the AP star network,I just use one AP and one ED, and the ED program works very well(has been tested), now I'm debugging the AP program

I find a problem, when the ED reset, SMPL_Init,then trigger the AP sCB callback function, the sJoinSem++, then main function enter the

        if (sJoinSem && (sNumCurrentPeers < NUM_CONNECTIONS))
        {
            while(SMPL_SUCCESS != SMPL_LinkListen(&sLID[sNumCurrentPeers]))
            {
                NWK_DELAY(1000);
            }

            sNumCurrentPeers++;
            sJoinSem--;
        }

but in the LinkListen , the AP cannot reach the nwk_processlink()  function as I set a breakpoint, this means the join is successful but the AP just cannot handle the Link packet or just cannot receive the link pcaket, but I'm very sure that the ED send the LinkRequest successfully.