Try that:
var testvar;
function main()
{
wait(1);
enet_send_var(_str("testvar"),BROADCAST);
}
ANet should give an error like that: "ANet-DLL: Error in enet_send_var! Bad ClientID!".
Tell me if this error is also shown when you run the .exe. (Please post the acklog.txt again)
I also need to know your GS Version and Edition and the ANet Version you are using.