[Dayrion]

Firstly, intend your code because this one is clearly bad to see.
This one is perfectly working for me.

PHP код:

CMD:jetpack(playerid)
{
    if(!IsPlayerAdmin(playerid)) return 1;
    if(GetPlayerSpecialAction(playerid) == SPECIAL_ACTION_USEJETPACK) ClearAnimations(playerid);
    else SetPlayerSpecialAction(playerid, SPECIAL_ACTION_USEJETPACK), SendClientMessage(playerid, -1, "You have spawned  jetpack.");
    return 1;
}