Routing Error Receive Port to Send Port

I have a Receive port that picks up files from a folder and a send port that delivers them to a different folder. The data in the files is in XML and corresponds to a specific schema. The Receive and Send ports both use the pass-thru pipeline. When I bind the send port to the RecivePortName using filter options everything works ok. The files are moved from the source folder to the destination folder. If I bind the send port to to the MessageType property, which was set in a previous step, the files are succeffuly moved but I get the following error:

Event Type: Error
Event Source: BizTalk Server 2006
Event Category: BizTalk Server 2006
Event ID: 5753
Date:  11/21/2006
Time:  3:16:50 PM
User:  N/A
Computer: ***********

Description:
A message received by adapter "FILE" on receive location "Receive Location1" with URI "C:\B2BInternal\CustPurOrders\*.xml" is suspended.
 Error details: The published message could not be routed because no subscribers were found. This error occurs if the subscribing orchestration or send port has not been enlisted, or if some of the message properties necessary for subscription evaluation have not been promoted. Please use the Biztalk Administration console to troubleshoot this failure. 
 MessageId:  {0FBF7379-2A84-48C6-BA31-E8ABC85AAF42}
 InstanceID: {F9CEE0A8-1134-4D71-92B3-04F71E506B6E}

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 Deliberately mis-spelling the MessageType results in the same error message and the files are NOT moved.

 Is it necessary to use some pipeline other than the pass-thru if you are going to reference context properties?