Tutorial Problem: schema validation errors

Hi,
already trying to go through the K2.net - BizTalk - Tutorial - Example, here's my newest problem:
After I filled out the flight request form in Infopath, I get the message in the K2 Travel Tasks List, that there's a new Request waiting.
When I try to open this Form I get the Error Message:

Infopath cannot open the following file:Manager%20Approval%20Event.K2MEGASRV_19_41.xml
The form contains Schema validation errors
Details:
Element '{http://schemas.microsoft.com/office/infopath/2003/myXSD/2004-03-06T19:29:49}_K2' is unexpected according to content model of parent element '{http://schemas.microsoft.com/office/infopath/2003/myXSD/2004-03-06T19:29:49}myFields'.

Thank you very much,

steveO


p.s.: I did solve my last problem with help of the very good answer to my last threat!!! Thanx!!!