Unable to connect to database inside Lambda function with VPC

I'm really not sure if this is an issue related to developmentseed/geolambda or osgeo itself.

I'm using geolambda/python layers to access some files in s3 from inside a lambda function. My goal is to send data from s3 to a database. The database is a postgres+postgis in RDS on amazon AWS using VPC. The lambda is using x86_64 with Python 3.7 as it should. I've already configure lambda's VPC and permissions correctly, so I can connect to the database using psycopg2. However, when I try to create the connection with `conn = osgeo.ogr.Open(connectionstring)`, the object conn is None.

I know that everything in connectionstring works, because I can connect to that same database from another computer in the exact same way.