FME : Value of attribute could not be converted to type 'date'

I am unable to integrate new data into a PostGIS table with FME, I get this error message. Yet, the original data in the Shapefile is already in date type. Some of the values are just 00000000 (when date is unknown), while others are YYYYMMDD.

Value of attribute ‘xxx’ could not be converted to type ‘date’.
Feature will be logged and skipped

Attribute(encoded: UTF-8) : xxx has value `00000000′

Attribute(encoded: UTF-8) : xxx has value ‘19880101’