SQLCODE Error -122

I'm not used to SQL a lot, so maybe my question is so dumb, don't be hard with me guys ;)

So, this is my table PEOPLE, and what i want is with a query is find the people that are not in an expecific age, but im getting an error.

    PEOPLE
+-------+------+---------+
| NUMPOL|  MCT |  PRODNUM|
+-------+------+---------+
| 98552 | 1054 |   9704  | 
+-------+------+---------+
| 89854 | 0985 |   5014  | 
+-------+------+---------+
| 78542 | 1054 |   9704  | 
+-------+------+---------+
| 98552 | 0965 |   9704  | 
+-------+------+---------+
| 98552 | 4222 |   9704  | 
+-------+------+---------+

I'm trying to run this query

SELECT NUMPOL, MCT, PRODCO
FROM  PEOPLE                         
WHERE MCT NOT IN (1054,0965) AND PRODNUM='9704'
GROUP BY NUMPOL

And this is the error that I'm getting, I tried to solve it googling but never could find an answer because I can't find why it told me that the select list is not valid:

SQLCODE = -122, ERROR:  COLUMN OR EXPRESSION IN THE SELECT LIST IS
NOT VALID

Solved

TRY :

SELECT TEAM, [NAME], AGE
FROM  PEOPLE                         
WHERE AGE NOT IN (20,21,22,23) AND GEND='F'
GROUP BY TEAM

NAME is an SQL keyword.

Read the error message :

COLUMN OR EXPRESSION IN THE SELECT LIST IS NOT VALID

Since it mentions the "SELECT LIST", inspect the SELECT LIST :

NUMPOL, MCT, PRODCO

Look for where there's a column named "PRODCO" in your table.

Group by has some rules

SELECT NUMPOL, MCT, PRODCO
FROM  PEOPLE                         
WHERE MCT NOT IN (1054,0965) AND PRODNUM='9704'
GROUP BY NUMPOL,MCT, PRODCO