HL7Exception: The version 2.3.CustomZSegments is unknown.

Hi!

I'm working on creating the Z segments and I followed the instructions and created the custom class but its not parsing and giving the error 
NHapi.Base.HL7Exception: 'Can't find message class in current package list: ADT_A04'

HL7Exception: The version 2.3.CustomZSegments is unknown.

I think I missed some crucial step here and there. Your help will be appreciated.
