I don't know why, but my file located at "FileStore/tables/train.csv" is not readable using pandas in the Databricks platform. I tried :
pd.read_csv("/dbfs/FileStore/tables/train.csv")
and got
FileNotFoundError: [Errno 2] File /dbfs/FileStore/tables/train.csv does not exist: '/dbfs/FileStore/tables/train.csv'