The problem is that a func_explosive can’t have a "death’’-event in the script…
see also: http://www.splashdamage.com/index.php?name=pnPHPbb2&file=viewtopic&t=12701 ]UBC[ McNite had the same problem.
Use a script_mover instead and give it the key/values like in the image below. You also need a script_multiplayer in your map. This example asumes that the axis needs to destroy the door to win the game…

here’s the script part:
game_manager
{
spawn
{
// Game rules
wm_axis_respawntime 1
wm_allied_respawntime 1
wm_number_of_objectives 1
wm_set_round_timelimit 20
// Stopwatch mode defending team (0=Axis, 1=Allies)
wm_set_defending_team 0
// Winner on expiration of round timer (0=Axis, 1=Allies)
wm_setwinner 0
}
trigger door_destroyed
{
// Set the round winner: 0 == AXIS, 1 == ALLIED
wm_setwinner 0
wait 1500
// End the round
wm_endround
}
}
door
{
spawn
{
}
death
{
trigger game_manager door_destroyed
}
}