cs1061 не содержит определение

public void Operate()
{
    long[] ev_times = GetEventsTimes(150);

    long[] ev_type = GetEventType();
    long[] ev_user_id = GetUserIdofEvent();
    long[] ev_door_number = GetDoorNumberofEvent();
    long[] ev_card_number = GetCardNumberofEvent();

    DataStore skdp_tcp = new DataStore();

    // ==== заполняем 11 регистр

    skdp_tcp.Add(ev_times.Length);
    skdp_tcp.Add(ev_type.Length);
    skdp_tcp.Add(ev_user_id.Length);
    skdp_tcp.Add(ev_door_number.Length);
    skdp_tcp.Add(ev_card_number.Length);

    // 12 регистр

    for (int i = 0; i < 150; i++)
    {
        ushort[] reg = new ushort[7];

        reg[0] = (ushort)(ev_times[i] >> 48);
        reg[1] = (ushort)(ev_times[i] >> 32);
        reg[2] = (ushort)(ev_times[i] >> 16);
        reg[3] = (ushort)(ev_times[i]);

        int t = GetEventType(ev_type[i]);
        int tid = GetUserIdofEvent(ev_user_id[i]);
        int td = GetDoorNumberofEvent(ev_door_number[i]);
        reg[4] = (ushort)((t | tid | td)>>64);          

        reg[5] = (ushort)(ev_card_number[i] >> 96);
        reg[6] = (ushort)(ev_card_number[i] >> 80);

        for (int j = 0; i < 7; j++)
            skdp_tcp.Add(reg[j]);
    }
}

Ошибка cs1061

Datastore не содержит определения add