Can't insert a Child data

I have to table,

MainTableA - id, description

TableAhasa- MainTableA_id(FK), OtherTableB_id(FK)

I got an error when doing inserting new record in child

Firstly, I inserted in a MainTableA (Flush Changes ) and got its id

Then, I inserted into the TableAhasa (It failed here)

How can I solve this problem? I would like to maintain my logic. I tried to set the "Is Managed" to true. in the relationship still didn't work. Any idea.