使用DSP6748做udp通讯调用udp_sendto时返回ERR_VAL

我使用6478做udp通讯，但调用udp_sendto时返回ERR_VAL，进入函数内部发现是
if (ip_addr_isany(&PCB->local_ip)) [
/* use outgoing network interface IP address as source address */
src_ip = &(netif->ip_addr);
] else [
/* check if UDP PCB local IP address is correct
* this could be an old address if netif->ip_addr has changed */
if (!ip_addr_cmp(&(pcb->local_ip), &(netif->ip_addr))) [
/* local_ip doesn't match, drop the packet */
if (q != p) [
/* free the header pbuf */
pbuf_free(q);
q = NULL;
/* p is still referenced by the caller, and will live on */
]
return ERR_VAL;
]在这段代码处报错，不知道是怎么回事？