Speed Change

CMD:changemyrunspeed(playerid)
{
   new string[ 45 ], Float:vx, Float:vy, Float:vz, Float:speed;
   if(sscanf(params, "f", speed)) return SendClientMessage(playerid,-1, "/changemyrunspeed (value)");
   GetPlayerVelocity(playerid, vx, vy, vz);
   SetPlayerVelocity(playerid, vx * speed, vy * speed, vz * speed);
   format(string, sizeof(string), "Your Run Speed Is Currently: %.1f.", speed);
   SendClientMessage(playerid, -1, string);
   SetPVArInt(playerid, "Speed", speed);// this saves the speed
   return 1;
}
public OnPlayerUpdate(playerid)
{
    new speed = GetPVarInt(playerid, "Speed");// this gets the speed
    if(speed !=0)// this looks if the speed that he setted was not 0
    {// now set his velocity
        GetPlayerVelocity(playerid, vx, vy, vz);
         SetPlayerVelocity(playerid, vx * speed, vy * speed, vz * speed);
    }
    return 1;
}