Power BI Direct Query and created columns with DAX

Question

I'm working on a project to ameliorate my skills using power BI

i created 3 tables on Oracle DB (data_2018, market segment and meals) i imported the data on power BI with direct query using this statement :

select * from data_2018 
left join  meal on data_2018.meal = meal.meal 
left join client_segment 
on data_2018.market_segment = client_segment.market_segment

then i created the following columns on DAX to calculate the income of the hotel

total_nights = Query1[STAYS_IN_WEEKEND_NIGHTS] + Query1[STAYS_IN_WEEK_NIGHTS]
room_no_discount = (Query1[DISCOUNT])* Query1[total_nights] *Query1[ADR]

1-i can't display the column room_no_discount in my visuals and i get the following error 2-when i try to make visuals using one of the join keys (Meals or Market segment) i always get this error

Thanks in advance for your help