Does my clapboard siding have tyvek, if so is it a problem?

I doubt that the Tyvek is the problem. It is suppose to minimize air infiltration and heavy water leaks but not water vapor. I suspect that water is getting into the house and behind the clapboards in some other fashion.

See the info at the site below:

http://www2.dupont.com/Tyvek_Weatherizat…