SimpleLinkHttpServerCallback not triggering in sample App(out_of_box )

i devolop a androd APP ,send a post request,param is "__SL_P_ULD=LED1_ON" ,IAR open Ti sample project(named out_of_box),then  set breakpoint at SimpleLinkHttpServerCallback function,then trigger normal.     but then param is not  "__SL_P_ULD=LED1_ON"(such as “ABC”..),send a post request ,SimpleLinkHttpServerCallback could not by trigger.what 's wrong ?

static unsigned char POST_token[] = "__SL_P_ULD";

void SimpleLinkHttpServerCallback(SlHttpServerEvent_t *pSlHttpServerEvent,
                                SlHttpServerResponse_t *pSlHttpServerResponse)
{
    switch (pSlHttpServerEvent->Event)
    {       
        case SL_NETAPP_HTTPPOSTTOKENVALUE_EVENT:
        {
            unsigned char led;
            unsigned char *ptr = pSlHttpServerEvent->EventData.httpPostData.token_name.data;//..................breakpoint is here.

            //g_ucLEDStatus = 0;
            if(memcmp(ptr, POST_token, strlen((const char *)POST_token)) == 0)
            {