Terraform AWS RDS module is not able to create db subnet group

Hi Folks,

My question is in regard to the following module:
https://registry.terraform.io/modules/terraform-aws-modules/rds/aws/latest#input_apply_immediately

I have used the following parameters to create AWS DB Subnet Group along with AWS RDS Oracle instance:

create_db_subnet_group                              =  true
db_subnet_group_name                                = "oracle-subnet-grp"
db_subnet_group_use_name_prefix                     = true

But I get the following error when I run terraform apply:
Error: Error creating DB Instance: DBSubnetGroupNotFoundFault: DBSubnetGroup ‘oracle-subnet-grp’ not found.

I don’t understand why Terraform is trying to find the DB Subnet Group “oracle-subnet-grp” instead of creating it.