can a message just disappear between the call to sendto() and the sending network card without notifying the caller?

Question

I send a datagram (6740 bytes) with sendto() to another host on the same LAN. Often there is no problem, and the other host got the datagram. But sometimes the datagram disapears, it never reach the local network interface, I have seen this with wireshark. But the sendto() function does not indicate any problem (i.e. returns -1). It returns 6740. I have also looked with strace, and everything seems to be ok.How can it be that sendto() says that everything is ok but nothing is sent on the interface? I am using ubuntu 10.04 and the ordinary c function sendto() (but via the ACE library). How can I investigate this further? The main question is probably: can a message just disappear between the call to sendto() and the sending network card without notifying the caller?