Can't show all records with the same id while join in oracle xe 11g - sql

Question

I'm getting this message while using this query, is there anything wrong?
SELECT t.tanggal_transaksi, o.nama_lengkap, SUM(td.harga * td.qty) total
FROM transaksi t, transaksi_detail td, operator o
WHERE td.transaksi_id = t.transaksi_id AND o.operator_id = t.operator_id
GROUP BY t.transaksi_id
Updated :
After using the answer from #Barbaros Özhan using this query :
SELECT t.tanggal_transaksi, o.nama_lengkap, SUM(td.harga * td.qty) total
FROM transaksi t
INNER JOIN transaksi_detail td ON ( td.transaksi_id = t.transaksi_id )
INNER JOIN operator o ON ( o.operator_id = t.operator_id )
GROUP BY t.tanggal_transaksi, o.nama_lengkap;
the data is successfully displayed. but, there are few problems that occur, the value of the same operator_id cannot appear more than 1 time. Here is the sample data :
+--------------+-------------+-------------------+
| TRANSAKSI_ID | OPERATOR_ID | TANGGAL_TRANSAKSI |
+--------------+-------------+-------------------+
| 1 | 5 | 09/29/2018 |
| 2 | 3 | 09/29/2018 |
| 3 | 3 | 09/29/2018 |
| 4 | 1 | 09/29/2018 |
| 5 | 1 | 09/29/2018 |
+--------------+-------------+-------------------+
After use the query command, the output is :
+-------------------+------------------+--------+
| TANGGAL_TRANSAKSI | NAMA_LENGKAP | TOTAL |
+-------------------+------------------+--------+
| 09/29/2018 | Lina Harun | 419800 |
| 09/29/2018 | Titro Kusumo | 484000 |
| 09/29/2018 | Muhammad Kusnadi | 402000 |
+-------------------+------------------+--------+
When viewed from the operator table, there are 2 data with the same operator_id that is unreadable
+-------------+------------------+
| OPERATOR_ID | NAMA_LENGKAP |
+-------------+------------------+
| 1 | Muhammad Kusnadi |
| 3 | Lina Harun |
| 5 | Tirto Kusumo |
+-------------+------------------+

Answer 1

You need to include the columns in the SELECT-list t.tanggal_transaksi, o.nama_lengkap, also in the GROUP BY-list but not the others like t.transaksi_id. So, you might use the following without any issue :
SELECT t.tanggal_transaksi, o.nama_lengkap, SUM(td.harga * td.qty) total
FROM transaksi t
INNER JOIN transaksi_detail td ON ( td.transaksi_id = t.transaksi_id )
INNER JOIN operator o ON ( o.operator_id = t.operator_id )
GROUP BY t.tanggal_transaksi, o.nama_lengkap;
Or this one :
SELECT t.transaksi_id, SUM(td.harga * td.qty) total
FROM transaksi t
INNER JOIN transaksi_detail td ON ( td.transaksi_id = t.transaksi_id )
GROUP BY t.transaksi_id;
P.S. Prefer using ANSI-92 JOIN standard rather than old-style comma-type JOIN.