BizTalk 2004 EDI Tutorial validation error

Hi, I am new to the Biztalk EDI adapter and I am working on the Base EDI tutorial provided by Microsoft: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/operations/htm/ebiz_prog_adapt_edi_iyyu.asp

And I got the following problems:

1. I try to use the 'X124010850Schema' to validate the instance 'ContosoPickupInstance.edi' and I got "(line:3 pos:7 filepos:161) error 46 [The source document in this mapping is not recognized. Check the mapping.]."

2. When I try to generate instance, I got "(msgnr:0 segnr:0)(line:0 pos:309 filepos:309) error 39 [The document type is not recognized. Contact the sender.]"

I set the Schema Editor Extensions to "Convast EDI  Schema Extensions" but it doesn't seem to recongize the document…  I have been working on it for a few days and still no clue, any help would be appreciated.  Thanks in advance.

 Alex.