为什么LWIP做TCP客户端通讯一段时间后数据会丢失？

LWIP1.4.1+ucosii操作系统，LWIP做TCP客户端，与服务器通讯一段时间后，调试信息打印出如下内容：
Assertion "unsent_oversize mismatch (PCB vs. last_unsent)" failed at line 443 in ..LwipLwip1.4.1srccoretcp_out.c
Assertion "tcp_receive: valid queue length" failed at line 1031 in ..LwipLwip1.4.1srccoretcp_in.c
Assertion "already writing or closing" failed at line 1356 in ..
Assertion “tcp_write:pbufs on queue=>a least one queue non-empty”failed at line 327 in ..lwiplwip1.4.1srccoretcp_out.c
请问有知道的朋友们吗？这个该怎么解决？希望有知道的同学明示一下，谢谢