Request headers missing in message handler when using CORS

I have been trying to fix this for a week and I have not got any further.

This relates to a post I did last Saturday: http://forums.asp.net/t/2022456.aspx?Problems+using+CORS+and+a+message+handler

Basically I have implemented CORS in my Web.API and it works just fine. I have also got a message handler in there and the calling clients adds request headers. But when I hit the message handler they are not there. The is a header Access-Control-Request-Headers with value accept, x-signature, x-password, x-psk, x-username, x-stamp which are the 5 headers the client sent.

Later when the code hits the controller I can see the 5 request headers.

If I was to run the client on the same domain and disable CORS the 5 request headers are available in the message handler.

Spent 3 hours of process of elimination and I will admit I am beat for now.

Please help if you can.

Thanks,

Dave Johnson.