[Pinguinn]

You were checking for "IsJumping" (under OnPlayerKeyStateChange), instead of "SuperJumpEnabled" (command)

pawn Код:

new
    SuperJumpEnabled[MAX_PLAYERS],
    Float:pX,
    Float:pY,
    Float:pZ;

public OnPlayerKeyStateChange(playerid, newkeys, oldkeys)
{
    if(newkeys == KEY_JUMP && SuperJumpingEnabled[playerid] == 1)
    {
        SuperJumpingEnabled[playerid] = 0;
        GetPlayerVelocity(playerid, pX, pY, pZ);
        SetPlayerVelocity(playerid, pX, pY, pZ +0.4);
    }
    return 1;
}