[Users] LCR module Problem

Hello, Im configuring Openser with LCR module and Im having an extrange behavior, I have 2 gateways, GW1(preference1) and GW2(preference2), GW1(pref.1) / \ ClientA --> OpenSer --> Client B \ GW2 (pref.2) / When I call from Client A to Client B using GW1, all works fine, its the same when hang up Client B or Client A, but when GW1 fail(I provoke it changing codec) and use failure route (GW 2) then if Client A hang up all works fine, but the problem is when is Client B who hang up, its like a new conversation, GW 2 send BYE to openser and Openser just send "503 Service Not avilable - No gateways" to GW2, but doesnt send nothing to ClientA, any idea ???? Thx in advance this is my basic configuration( I have attached full config file): route{ if (!method=="REGISTER") { record_route(); }; if (loose_route()) { append_hf("P-hint: rr-enforced\r\n"); route(1); }; if (!uri==myself) { append_hf("P-hint: outbound\r\n"); route(1); }; if (uri==myself) { if (method=="REGISTER") { save("location"); exit; }; if (method=="INVITE") { if (!lookup("location")) { if (!load_gws()) { sl_send_reply("500", "Server Internal Error - Cannot load gateways"); return; }; }; if (!next_gw()) { sl_send_reply("503", "Service not available - No gateways"); return; }; }; }; }; t_on_failure("1"); route(1); } route[1] { if (!t_relay()) { sl_send_reply("666","t_relay fallido"); return; }; exit; } failure_route[1] { if (!next_gw()) { t_reply("503", "Service not available - No gateways 1"); return; }; if (!t_relay()) { t_reply("666","t_relay fallido"); return; }; }