document type does not match any of the given schemas

hi

in a next stage of my BizTalk app i have a new error…

in a message queue there are messages like this:

<?xml version=\”1.0\”?>..<string>Voorruit</string>

this i made in a windows service with this code:

[quote:e03c824827]MessageQueue productqueue = new MessageQeueu(@\”.\\Private$\\Productsysteem\”);
System.Messaging.Message pq = new System.Messaging.Message();
pq.Body = strProduct;
productqueue.Send(pq);[/quote:e03c824827]

for sofar this works to get in the queue. but now this:
In BizTalk i made a receive port who receives the messages of the queue.
I made a xsd schema for the incoming message
i transform the message to a sendmessage (also almost the same)
(the sendmessage is a flatfile schema)
and then i send it back to a folder in a flatfile.
off course i made a new send-pipeline with the flat file assembler.

The only thing he does correct is receiving the message (although that’s what i think)

this is the error he gives:
[quote:e03c824827]There was a failure executing the send pipeline: \”Webshop.SendProductieFF,Webshop,Version=1.0.0.0,Culture=neutral,PublicKeyToken=bac8947f50b16b59\” Source: \”Flat File assembler\” Send Port: \”Webshop_1.0.0.0_Webshop.MainProcess_SendProductsysteemFF_bac8947f50b16b59\” URI: \”D:\\Productsysteem\\Order.txt\” Reason: The document type \”string\” does not match any of the given schemas.[/quote:e03c824827]

thx in advance.
Thomas