I’ve a table data

CREATE TABLE your_table 
(
    ER  VARCHAR(512),
    MONTH   VARCHAR(512),
    SCENARIO_CD VARCHAR(512)
);

INSERT INTO your_table (ER, MONTH, SCENARIO_CD) VALUES
    ('AAA', '1', 'BUDGET_N'),
    ('BBB', '1', 'BUDGET_N'),
    ('BBB', '1', 'BUDGET_N_1'),
    ('AAA', '1', 'ACT_N'),
    ('AAA', '3', 'BUDGET_N'),
    ('BBB', '3', 'BUDGET_N'),
    ('BBB', '4', 'BUDGET_N_1'),
    ('AAA', '4', 'ACT_N');

SELECT * FROM your_table

ER  MONTH   SCENARIO_CD
AAA 1   BUDGET_N
BBB 1   BUDGET_N
BBB 1   BUDGET_N_1
AAA 1   ACT_N
AAA 3   BUDGET_N
BBB 3   BUDGET_N
BBB 4   BUDGET_N_1
AAA 4   ACT_N

I’m trying to apply this logic: For the same Month and ER, I need to display only lines with budget_n and ACT_N, odenpendently from budget_N_1

I expect a result like
enter image description here

I tried the following scrit, but it returns wrong results

SELECT * 
FROM your_table
WHERE ER+MONTH in 
(
SELECT ER+MONTH as ERMONTH
FROM your_table
GROUP BY ER,MONTH
HAVING COUNT(CASE WHEN SCENARIO_CD = 'BUDGET_N' THEN 1 END) = 1
       AND COUNT(CASE WHEN SCENARIO_CD = 'ACT_N' THEN 1 END) =1  
)