CC2540如何一次发送俩个数据？

 // Do a write
        attWriteReq_t req;
       
        req.handle = simpleBLECharHdl;
        req.len = 2;  
        //req.value[0] = simpleBLECharVal;
        req.value[0] = 1;
        req.value[1] = 2;
        
        req.sig = 0;
        req.cmd = 0;
        status = GATT_WriteCharValue( simpleBLEConnHandle, &req, simpleBLETaskId );   

这是我修改的发送端，当reg.len=1时，接收端可以进入simpleProfileChangeCB这个回调函数，但reg.len=2或以上都无法进入回调函数，请问如何修改